Please help.

Ok so my husband and I are in our early 30's we have 2 kids he is diabetic and he's starting to have problems down there it won't get up or if it gets up we start and then goes down I mean i can see his frustrated face I asked him to go to the dr but doesn't want too, sometimes it makes me wonder that maybe im not doing things right ''sexually" or that maybe he's with someone else uuugh I don't know but I'm tired of this situation I love him and want to help but I just don't know how ¿Has anyone else been through the same situation? Please help me😔😔