I can’t tell from what you’ve written whether he’s cheating or not. How long have you been dating and is this the first time you’ve noticed this type of thing? There are lots of reasons why men his age aren’t interested in sex — from health issues, to fatigue to stress to disinterest. It could be any of those. I think you have to give it some more time to see if there are any other changes in the relationship. Once incident like this, even with the sweatshirt smelling like perfume or cologne, isn’t enough to be sure.