My opinion on this is that she was only acting like that because she was single. If you and her ever date exclusively, I don't think she would run around making out with random women. If it makes you uncomfortable, don't date her.
Are you looking for someone to marry specifically? Or are you just looking to date? Or will the dating maybe turn into marriage? Thats all the stuff you get to decide before you get attracted to a girl.
Just my two cents.