Do you know for a fact he doesn't find you attractive anymore or are you just assuming?
His testosterone level might have dropped, or he may be under a lot of stress. Both of which can lower the drive in a man. It is possible he isn't feeling very attractive at the moment. I don't know if you have tried it, but I would recommend a more aggressive pursuit of him, don't use subtlety. The other thing is you might want to gently suggest he get his testosterone levels checked.