Makes me wonder if they've played this little game before. "Let me try to make you jealous, because I'm still ticked off about what happened last week." And then it suddenly goes away just as quickly as it surfaced? Don't be surprised if that's at least part of it. Yes, the partner sounds like a real buffoon, but your instructor may be a master of this kind of head game. And, unfortunately, you are in the middle of it. I would play it coy, actually, and see if the opportunity arises to tell the partner that it appears there are some head games going on, and you feel sorry that they have to drag personal things into their professional lives. It's a formula for eventual disaster for them, not you. Keep your eyes open for other instructors, or even very good dancers at the studio who might be willing to help you on the side somehow.