I (18m) in my second relationship where I’ve tried to have sex with my partner but with each one I was never able to penetrate. With my first partner, I thought maybe she was just too tight, we could never get two fingers in without wincing and her telling me to stop, so it seemed like a reasonable conclusion. After several attempts on multiple occasions it never worked, and we broke up. Now in my current relationship I’m having the same problem as before and I’m starting to feel like it might be my fault somehow. It’s worth noting that she’s a virgin, but there was a considerable amount of foreplay and we tried 3 or 4 different positions and it just never went in. I tried guiding, she tried guiding, I’m not sure what the problem is or how to figure it out.

Is there something I can do to find the cause? Is this a common issue? Are there solutions or ways to help with penetration?