No sex

Everytime I ask my fiancee to have sex he makes up an excuse. Its nothing new. But it really hurts my feelings. He says I wait till the last minute or when he's stoned but if I ask any other time he still says no. He was at his mom's visiting the other day and was saying he wanted to do freakier things. Of course I'm thrilled but now that he's home he won't have sex with me. But if I offered to blow him he'd be all for it. I'm not really looking for advice just ranting. I know I'm not as skinny as I used to be or as put together so I'm sure that's why. But he still makes me feel beautiful. The sex is literally the only problem in our relationship. I'm just frustrated lol.