need a man's view on this.

So my husband and I rarely have sex anymore. And if we do i have to beg for it, which I hate doing. Every time he's hard I tell him we could solve that being doing it but even then he turns me down. I'm not the type of girl who allows or likes when a guy watches porn. If you're with me and you're horny you tell me I'll gladly help you out because I like sex too. my husband knows I hate when he watches it and would rather him not to. But i always find porn in his history. Why is it that he can get off to other people having sex but won't even have sex with me. like even when we do have sex it's not even that long and most of the time I don't even orgasm or cum. And then he just falls asleep after. Does he not find me attractive anymore? or maybe just doesn't want me anymore? I've talked to him about it and he says he's "tired" but he literally gets off work everyday at 3:30. I know he's not cheating on me but why won't he have sex with me??