help my sex life/ how to get it started again

So my boyfriend and I have been together for 4 years now. When we first got together we would have sex a lot. Now we hardly do maybe 2 a month. Now he is 30 and I am 23 and I try every day to initiate it and he never wants to. I have been trying for like 2 weeks straight now and he just doesn't want too. He said it's not me and there's nobody else and I believe it. He said that he just doesn't get the Urge anymore. He doesn't feel sexy anymore we have both put on some serious weight since being together.  Now I know sex isn't everything but I do crave it but much more I crave the closeness and intamacy. I've decided to stop trying to initiate and he said he would try harder to start. Any advice I really need it