My boyfriend cums in seconds?

My fiancé and me been together for three years and he still isn’t use to me. Lol. He dated someone before as well. I try to stop him and do foreplsy and rub against him to make my own self orgasm and he instantly cums it’s super annoying. I tried to stop him and it never works. He acts so selfish and I hate it. Any advice? I have tried talking to him many times even doing foreplay. I haven’t orgasmed in over a month.