I don't know what's happening

THIS MIGHT BE TMI!!

The other day I was having sex with my boyfriend, I was actually enjoying it but out of nowhere I had this urge to cry. It's not like he was hurting me or anything for me to start crying, i just did. This is not the first time it's happened either. I've felt like that before while having sex, except the first time it happened the guy was actually hurting me and it hurt so bad that I started crying. But my boyfriend is always really gentle and for some reason I started crying.. have you ever had a similar experience to mine?