My husband's sims are stuck at the "old friends" status in their relationship.
They've been living together for a few weeks and have twin boys. The option to get married doesn't appear in the moodlets, along with some other choice options like massage. (Poor guy just wanted to give a sim-preggo-version of myself a back massage and never got to .) Anyone else encounter this? I haven't seen it in my save so I don't know what he did wrong.

I was confused about this at first, also, and I sort of just assumed an answer for myself to make me content - it seems to be working with me, too.

I think you need to have your Sims in certain moods before certain actions to others. Also, talking and interacting with someone will bring up the interactions - talking to a love interest to the point of alluring or irresistible(depending on the traits) brings up options like marrying and the likes.

It's worked for me, maybe it will work for you? Hope it helps!

You need to make those options available by doing romantic things like flirting and kissing. Then the other person will think that you are flirty or being extremely flirty. Then those options will be available to you.

I saw posted somewhere that you may need to use the "Go Steady" interaction first, but like has already been said, you have to work up their social state first to have it show up. I haven't proposed marriage yet, but I have seen the option for Sims who were going steady.

See according to what my husband is telling me he has tried all that. (The twins didn't appear out of thin air, after all!) But I will tell him to keep an eye out for that particular moodlet.

Use the shy kiss, that opens up everything.