Oh wow. I am clueless. I think I just put some things together. Thanks for the comments, they added some perspective.
He's married. His wife also practices. I am also married (happily!!). His wife has always been polite with me, but is often more friendly with other people than me. I often have an easier time making friends with men than women. I don't think there are any better men on the planet better than my husband, so affairs are a foreign concept for me. Never even crossed my mind.
Sensei has made some comments about how people will follow their highest ideals, not yours, so you shouldn't judge them based on your ideals.
Possibly, it was some combination of one or both of them fearing an affair. Ugh. I don't think of myself that way! The idea of me as some sort of temptress is laughable!
So now, how to deal with that? I'm a little obstinate, so I'm not sure I want to give up the dojo that I love over something so dumb. And there are my female kohai that I feel a responsibility to be an example for.
Hmmm, maybe I should talk about how ugly and smelly he is in front of his wife....Or I could constantly talk about how great my husband is....lol. Ideas??
Insulting him probably isn't the best course, even if he isn't around when you do it. Actions speak louder than words; accept your position as a student, because regardless of the reason, he is uncomfortable with you being more than that. Make it clear that you're there primarily for the aikido... or start hanging out only when his wife is also present, or hang out with other students. Or get your husband on to the mat, too.