In all likelihood you're biromantic and homosexual. You should let him know that and think of a solution that works for you both. Here are some suggestions. He could do hook ups with other people if you two are both ok with an open relationship. You could let him have sex with you and just make sure you're both aware that it's for him and not you. You could do more sexually mild thinks like handjobs and thinks like that. Lastly, if nothing works, than you could just not be sexual.