4.25 girth

it sucks so fucking bad i can't stand it. Ive had two long term relationships, one is current but both of them never cum and they were both small. I feel like a failure of a man
They were small in boddy size? Because that has nothing to do with how big they are down there! I had a girlfriend who didn`t cum vaginaly and my girth is 5.7". No problem, I told her I loved it when she touched her clit while we had sex. Sex-life saved, she even squirted once

My girlfriend now come very easily, even on tiny 3" girth dildos. Some girls are vaginaly sensetive, some aren`t. And girls vary more in size down there than men.
An advantage of being thinner is that you may last longer, if premature ejaculation is not a mental thing, which it often is.
Get her to touch herself during sex, tell her it turns you on. And the two of you can try hitting the g-spot when you are in her, she can have a pillow under her ass or you can figgure out what works best for you.