Feeling undesirable

Hey! I hope you girls can help me with this. I'm 29 and my boyfriend is 24. We've been dating a little over 2 years. Naturally at first we were having sex all the time but it slowly started to decrease. It went from several times a week and a few times a day to just on Saturday mornings and now I'm lucky if I get it once a month. I've talked to him about it several times and he assures me that it's not me and that he wants to have sex but he just can't and I offer to give blow jobs (which I'm amazing at) but he even turns those done. We live together and he's very affectionate. He's constantly kissing me and cuddling me and tells me I'm beautiful. But it's been a year now that we only have sex maybe once a month. I asked him if he would be offended if I got a vibrator or a dildo and he said yes. I feel like I'm compromising all the time and I read blogs all the time about this issue and read advice on how to approach him about it and he says he's going to try to do things on his end to boost his sex drive but he doesn't make any effort and like I said it's coming in on a year where we only have sex once a month. So at this point I'm am getting rejecting constantly, can't have a dildo and masterbating can only do so much. I'm lost and alone and I don't know what else to do. Please help!!