SO Previously Married

How do you guys deal with the fact or react to your significant other being previously married? We were at his parent's house for Christmas and we were looking through a box of pictures. Out of nowhere a picture of him and his exwife at the wedding pops out. I was bothered and didn't want to look at any more pictures. He has a daughter with her and I understand that she will always be in the picture but it just bugs me knowing that at one point he loved her enough to marry her.