I think you're approaching this from the wrong perspective OP.
My DP is most likely to want to have sex in the week after her period, we have it the rest of the month sporadically, but during that week it's more nights than not.
Does she find me more attractive than week? Well probably yes, but it's not because I spontaneously get better looking one week in four, like some bizarre were-hunk.
It's because she's hornier, and not because she's seen someone on TV, or been watching porn or thinking about someone else, she just wants more sex.
It's the same for men too, stress, tiredness, how recently I've had sex all come into play when it comes to how in the mood we are.
Some men might be horny all the time, but most aren't, and it sounds like your husband has a particularly low sex drive, but that doesn't mean he doesn't fancy you, just that he doesn't fancy sex that frequently.
Your next point might be "but we used to have more sex", but the fact is that when you're in a new relationship, sex is new and exciting, and you have it even when you're not that horny because you don't know how long the relationship is going to last, so you'd better take every opportunity while you can.
When you've been together 15 years, you can be reasonably sure that the other person is still going to be around tomorrow, so you don't need to take absolutely every opportunity when you're not horny right that second.
I'm not saying that you don't have an issue OP, mismatched sex drives can be a fucker. But that's the issue you should be worrying about, not whether he's horny for you or just plain horny. That way madness lies.