This smells like a hack conflict. If this is a new issue, check any hacks you've added recently. If not, remove any hacks you have and see if the interactions are available. Pop on over to
SimWardrobe and snag a copy of the Hack Conflict Detector Utility if you don't already have one. Use it to check to see if any hacks are conflicting with each other. Also make sure your hacks are updated or cleared to work with AL.
...now if this is simply a case of not knowing how to find the interactions:
1.) Propose Engagement, obviously, is available via the 'Propose' menu when your Sims are both in love. LTR score has to be 70 or above.
2.) You can find a roommate only if your Sim is living in an apartment. To find one, simply use the newspaper, the telephone, or the computer. You can also ask other Sims to be a roommate if your relationship is high enough with them.
