Iv been in a serious relationship with a girl for about 2 years. I am 27 and she is 25. She is a great looking girl that is very outgoing and caring. My issue is her belief regarding casual sex.

When we first started seeing each other, but hadnt yet defined the relationship, she slept with a co-worker after about 1.5 months of us dating. We were seeing each other about 4-5 times a week(sex most nights together) at that point and I hadnt even thought about the need to have an "our we exclusive talk." She admitted that he was over at her place, but didnt tell me they slept together that night until about 6 months later(I knew the guy, so she feared I would tell people). We defined our relationship 3 days later.

I let this go and figured it was one mistake and she didnt technically cheat as she wasnt sure how I felt about her or if I was serious. Her past isnt crazy, she's had about 8-10 sex partners, but tends to go from one guy to the next with about a week in between.

I just found out a week ago that on the few occasions that she was single in her past, she would tend to date and sleep with multiple guys at the same time until the relationship was defined. This brought back my negative feelings regarding sexual partner overlap from our own past together.

Do you think it is normal for girls and guys to have multiple concurrent partners? She claims to always wear condoms when this occurs(even though she mentioned have condoms break 5+ times and using plan B 3 times in her past). Would you have an issue with her past or am I just being judgmental?