I don’t make my man hard anymore?

I know this is kind of stupid, but I like to tease my fiancé by crawling on the ground in booty shorts and doing a little twerking for him. Just being sexy trying to turn him on.. well tonight I was going at it for a GOOD few minutes while he watched and made commentary about how sexy I was etc, after a while I crawled over to his dick and it was completely soft. TOTALLY soft. I have a big booty and it’s one of my best features, I just don’t understand why it didn’t at least give him a chubby😞 I have really bad self esteem issues and have been considering cosmetic surgery for a while. I’m just hurt.. I tried to ask him why he wasnt turned on and he just says “his back hurts” but it seems to suddenly be a reoccurring excuse when I ask why I didn’t get him hard. I know if that was any other chick doing that or a video of one doing that he would have a boner.. our sex life is GREAT though. He gets hard when we have sex. I don’t understand. Anyone have thoughts on why he’s this way?