My game was quite calm till I threw a gift giving party shortly after moving her boyfriend in, I invited his friends and they all thought she was hot now they keep sending her love letters and gifts, two uninvited female guests at the party do the same to her boyfriend as well.
My two got the eternally faithful moodlet come up just as he was turning down yet another date call, from a teenager no less, I realise he hadn't long aged up himself but I didn't expect that.
Pam, I get the feeling the letters go in a predetermined cycle, my sim had the same with her boyfriend, each letter a bit more than the last till the last one said he was madly in love with her. But he is, he thought she was hot on first meeting which didn't surprise me as these are my usual pairing and they are always mad about each other, but maybe despite the game saying one thing the spark isn't quite there for your two.
I've noticed that with sims, sometimes they meet somebody and it just clicks and I love that, it's nice when they are autonomously romantic rather than me feeling like I'm pushing them into it. I gave up a long time ago choosing for them, I always let them choose themselves now even if it isn't who I would have gone for as they seem much happier that way. I'm not sure if this system will help or hinder that at the moment.