Un satisfying sex

So as of the past 6 or so months my boyfriend has been having trouble lasting literally longer then 2-3 minutes. And especially if I'm on top so that's just out of the question now. I'm not sure exactly what to do lol I love him but our sex life is extremely frustrating for me right now. Is there certain methods anyone knows of I could suggest to him or different things such as food or something he could change in his lifestyle or what would cause it even. When it first began it was funny to me because I felt he just couldn't help himself and I had just become more attractive to him but it's to the point I can't help but whine afterwards and get slightly upset. Pleeeeeease help