Ladies, help me understand this please

While I was doing it with my girl, the 1st round went fairly well. During the second round, she started crying that it's painful for her to take it even though we were using the same position as the first, missionary with her legs on my shoulders. She was wet even creaming when I took it out, yet she said it hurt even entering in,and would push me out with her fingers whenever I thrusted until I gave up. Now I don't know what to think of this since I'm not much experienced sexualy that's why I need to hear your perspectives.