Its Twallan's SuperComputer Mod http://ts3.tscexchange.com/index.php?topic=1300.0

I had a similar thing although it didn't involve foreign sims. A female from my active family, who had no previous committed relationships fell in love with a guy also from the main hood, he had an ex girlfriend. He moved into my active household and the two of them went to Egypt, during that trip I decided to advance the relationship to BF/GF but the option never came up. When I looked in her relationship panel for him, under partner it gave the name of his ex girlfriend with the ex gf icon so I waited until they returned to the main hood. On return, in the relationship panel he was now listed as single so I tried again but nothing would get the option to appear even when totally irresistible. No option to break up with his ex appeared when I called her over and she too was listed as single. The only way I could advance the relationship was by using the relationship option on Twallen's SC to make them go steady then they were able to propose marriage like normal.

Reading the comments about marriages occurring too quick, I'm beginning to wonder why I'm seeing the opposite. In 3 seperate towns  around 70% of sims have remained unmarried by time they've turned elder (slightly modified normal agespan). Today I've had to reset age on around 30 because they were within a couple days of turning elder and still no partner (romantic interests but nothing more). I've now tweaked the same xml to 80 for all 3 values to see if an increase occurs and after 10 sim days the result is 3 new marriages. I'm wondering if its due to having a large amount of singles in my hood, its somewhere around 70 or 80 I think. I guess it proves different town set ups produce differing results in storymode which to me is the whole point of having one.

With what you've just said about them splitting up immediately, doesn't that prove lowering the values in the xml does significantly reduce the chance of the relationship advancing? Unless I misunderstood what you meant. 

The romantic interests which reappeared were with the exact same sims they had prior to marriage. I received no story mode message to say they had been interacting again.

My understanding is, the hearts should be removed from sims when they marry but this only started happening on the last few builds of AM. So sims who married before this will still have the hearts and therefore still cheat.

I'm still seeing this happen on a new save. The hearts seem to be removed on marriage (appear to change to friendship) but then on several sims they reappeared. Out of 4 marriages I've just tested, I selected each sim on marriage and no hearts remained in the relationship panel but when I re-selected a little later they had reappeared on 4 of the 8 sims. All of these hearts were from previous relationships prior to marriage (I double checked an older save to make sure). I've no idea how this happened, there were no ASM romantic actions involving these during testing

I'm not sure because what they were up to before marriage didn't interest me. I noticed 1 of them did have an ex listed so I assume would suggest after. I'll check with the next couple the system marries.  Sorry I can't be more helpful.

EDIT: I've copied the town and just fast forward the active family to get more marriages. Each time there was a marriage I selected the couple and looked for romantic interests remaining there was none, this was the case for 4 different couples. On the 5th couple, when I went and checked I also checked on 2 more sims living with them who I knew had numerous romances. One of these had a romantic interest listed as 1 of the males from the previous 4 marriages so I went back and checked him and he now had 2 romantic interests and his wife 1. I'm certain these were removed when they married and somehow were reinstated neither have flirty/commitment issue traits. I also went back to the other couples and 1 male had also regained a romantic interest, no romantic ASM notifications were received involving these during testing. Looking back on the save before, when these couples were engaged, the same sims were listed as romantic interests.

I still don't think this is working correctly even in brand new neighbourhoods. I started a fresh Sunset Valley 4 real days ago which is now in sim week 5. Sims which were married by ASM are constantly cheating with others, both married and single. I've just looked at 3 seperate sims as an example, 1 with family orientated trait had a wife plus 3 romantic interests and 2 other sims both with unflirty trait have a husband/wife and 2 romantic interests each. So it isn't because of flirty/ commitment issue traits.

I download the latest AM before each play session so this isn't the result of old versions.

This was with the latest AM I've just checked to make sure (dated 23/8 at 01.03) and a brand new town so no pre existing relationships.

On the point posters have been making regarding romancing. I noticed very few sims were actually getting married in my played neighbourhood with the last few updates so did a 4 week wolfrun on it which confirmed this.

Following this I created a new town using the latest AM and populated it with 25 male and 25 female YA's all at the beginning of the lifestage with random traits and a broad mixture of lifetime wants. I ensured there was plenty of cribs and beds and affordable housing. I then played through until they became elders the result was only 9 marriages and 14 offspring so therefore a dead town.

I realise this was a small population but the same thing is occurring in my other town which currently has around 160 sims in it. The majority now seem preoccupied with skilling at the expense of marriage and kids. I'm all for realism but most people in the real world manage to combine a family with a career. As the story progression is now, in my experience, there doesn't seem to be a way of keeping a town alive and with a decent gene pool without a great deal of intervention ie. manually marrying most of the population or constantly shipping in new sims.

The few sims in this test hood who did actually get married were constantly having affairs despite having neither the flirty or commitment issues traits, actually a couple had the unflirty trait which was a surprise. Do we have to select each married sim and use 'dropoldloves' to stop this? if so is there anyway to make this automatically happen on marriage or a global command?

I've just completed another 4 week wolfrun because I was getting very few marriages despite having lots of singles romancing. Of the marriages occurring during this time at least 1 of the couple had flirty, hopeless romantic or family orientated traits except in 2 cases. In these 2 cases the only common trait I could find was unflirty.

I've also reported the same thing regarding relationships and marriage in another thread. After an 8 sim week wolfrun following 3 weeks normal play only singles with hopeless romantic, flirty or family orientated traits initiated relationships.

I'm a long time lurker and user of Awesomeware but never previously had a reason to post.

I've just completed a 8 sim week wolfrun using the latest ASM build on a pre existing neighbourhood. There was a couple of things I noticed concerning romances.

Firstly, although the vast majority of married sims initiating romances had either the flirty trait or committment issues, I saw at least 1 with hopeless romantic trait doing this. I've read previously this isn't supposed to happen but I'm not sure if a fix has been attempted yet. Secondly, the only singles initiating romances have either flirty, family oriented or hopeless romantic traits. I realise traits should affect romances and I wouldn't like to see married sims without flirty or committment issues having affairs but I would like to see singles with a much wider range of traits initiating romances. The way it is at present means only a very small number of sims will marry and breed therefore leading to a population decline and a rapidly decreasing gene pool without player intervention.

On another note, I know the freezing issue has been mentioned a few times and Pescado said he doesn't want to hear about it if it can't be reproduced. Since starting to use ASM on a few occasions I've experienced a freeze where everything stops except the plumbbob keeps moving and birds fly over the lot which can only be shut down using task manager. During this wolfrun, this occurred roughly every 9 sim days it was random and couldn't be reproduced when the save was reloaded. If I don't have ASM enabled and use EA story mode or ISM with AM instead, this never happens so seems to be in some way connected to ASM. Sorry I can't be more specific but thought I would mention anyway please ignore if unhelpful.

Thankyou for a great mod and a story mode with alot of potential.