So I have those two sims living together, they are "romantic intersest" to each other. They've had twins a few days ago. I would like them to get married, but I can't find the option, nor can I find the "go steady" option I read about somewhere. Is it that their relationship is not high enough? The green bar is almost full, but one sim still has to discover two traits about the other, could that be the reason? Or does the game consider that living together is enough and marriage between roomies isn't possible? I really don't know what to do with them. I have read several things about marriage in Sims, but could not get an answer to that specific question.

Thanks for your answers!

You need to do a bunch of romantic interactions before the go steady, get engaged, and get married options appear.

Ok, thank you, I'll keep doing that. I thought that whoohooing a dozen times and having two babies would be enough but it seems they reeeeaaaally need to love each other to commit. Too bad one of my sims is turning into an elder in three days.

What audioromance said. Romantic interactions, go steady, get engaged, and get married are all available earlier in relationships and earlier in interaction trees for hopeless romantics.

I had a hopeless romantic loner. He had romantic interactions available very early in relationships, but they were marked as subject to a negative modifier because of his loner trait.

I found the easiest way to work it is to basically flirt, kiss, embrace, massage, make out etc etc until you see the "go steady" option which should appear under the romantic interactions menu. It took me awhile to figure that out.

My sim was developing a relationship with a townie and spun the wish to kiss her. I promised the wish and arranged to meet the object of my sim's affection at the park. She was old!

Well, that worked! Just in time, my sim's birthday is tomorrow.

gotchan : haha, I can imagine your sim's surprise! I'll turn aging off next time I'm in a situation like yours

I still cant beleive my Sims had sex AND got preg without being more than 'Best Friends'.