I don't know if this is a dumb question or not but I can figure out how to get to the next level with a sim higher then "Romantic Interests"
The problem is that I see some menu options very rare or almost never at all. I only see "convince to break up with 'so n so'" , "message", "whisper in ear" and such romance options very rare.. is it me or is something wrong with my game?
Here is pics for example(click on them to make bigger)..
This is what my Romance options looks like 99% of the time:


And this I almost never see with any of the sims I have ""Romantic Interests" in:

(notice the one added 'break up' option. and i am sure there are other Romance options missing...

How do u become a partner with someone? Ask them to move in? Marry them?
What am I missing and why?

Do you have any social interactions CC?
Remove all CC and test with new game and test on random couple?

I notice in the first pic that the social bubble in the top left says "Bebe thinks James is being flirty" - in the "being flirty" stage, not many interactions are available. If you keep flirting for long enough, the bubble will switch to "X thinks Y is being very alluring", at which point more interactions are available; and the next, and highest, stage, is "X thinks Y is being extremely irresistible", which enables all romantic interactions.

The same system applies with friendly interactions - at the "X thinks Y is ok" stage, you don't have, for example, the Friendly Hug or Express Fondness options; those become available as you move into "X thinks Y is being sociable", "X thinks Y is being friendly", etc stages.

At one of the later two flirting stages, I forget which one, you'll see the option to "Propose Going Steady" (if the other sim is single); this will give you the boyfriend/girlfriend marker. If you don't like that, there are a few hacks available which change it in some way, though I'm not sure exactly how.