What Causes Cut On Penis Shaft During Intercourse?

last night my fiance and i were having sex, and it is always extremly hard to get started. well we were going for about 2 min and he yelled and pulled out. when he pulled out there was a thin cut on the top of his shaft. Is there something wrong with me or could it just be that the ridges on the top of my vagina cut him. also could this have anything to do with pregnancy. idk if i may be pregnant