I got the Eternally Faithful thing by the time that term was over and it automatically sent him home with me.
However since they went home there never is an option to propose marriage, just wohoo or try for baby and other romantic options.
I have seen the propose option at Uni, so I believe its possible.
I've been having the same problem :| Does anyone has solution or something to it?
Aside from their current relationship status, factors that may affect the kinds of interactions available include the life state, age and whether or not the two come from the same family.
Relationships between Sims are not always romantic. If the two don't get along, their interactions can even be hostile.
Maybe your sims know something about him you don't.
In which case, consider it lucky you never had to find out.