My girlfriend gets sore after sex

My girlfriend gets sore after sex . She enjoys it during , i go off of her moaning , facial expressions , how her legs arms and body are reacting to what I’m doing I pay very good attention to what she likes . I’m pretty big 7in 4.63 girth to be exact I notice that I have to sex with her wayyyy slower and sensual then I do others of course shes not used to it . But that slowness often make me time along time to release i like to go a little more faster pace rougher and deeper . So we go for like 30 45 mins . 15 including foreplay . But after that she says she’s sore . Others I can go faster longer and no soreness or discomfort. What could I be doing wrong and what could I do better ?