Kaidan Romance: Bugged?

I'm at the point in the game where I'm about to do the N7: Horizon mission (pretty far into the game). I romanced Kaidan in ME1 and Thane in ME2. I am attempting to pursue the romance with Kaidan again, since Bioware robbed me of my happiness by killing the only Drell I could ever love.

The problem is this: I have done all the right things with Kaidan, got him to join my crew, and have gone to see him often. Yet, for some reason, he has not invited me to dine on the Presidium. According to all the forums I've been able to find on the subject, he should have asked me by this point. Because he hasn't asked me, I haven't been able to do the Citadel DLC, because I don't want to spoil the romantic bit.

Is this a bug? I've done all the right things, been kind, blah blah blah. Last time I played (years ago), there was no problem. I am a tad bit more renegade this go around, but I'm still only at about 25%. WTF, over?