Is it normal for my girlfriend to spend holidays with her sorority sis

Is it normal for my girlfriend to spend the holidays with her Sorority sister and family? My girlfriend just recently pledge a sorority and has been pushing the social agenda real hard. She recently spent Thanksgiving with then which including her birthday that weekend. Which we were suppose to celebrate. Now she has made plans to visit her sorority sister and family again during the Christmas holiday. She wants to spend Christmas day with me and then go off for the rest of year through New Years. She met her sorority sister while she was pledging and met her family for the first time over Thanksgiving.

We've been dating for almost a year and she doesn't seem to think that there is anything wrong with what she's doing. She says they make a her feel like having a real family. That I'm her boyfriend and I should understand. I'm all for having friends and doing thing other things with other people from time to time. School is out for the year and the first thing she said to my after her last final. "I'm all yours baby" I work she doesn't and I have been supporting her with various expenses. I've already discuss my feelings with her about this, but yet she is still going.

So I would appreciate responses on what you would do in a situation like this. She says she loves me and I'm her everything, but for me actions speaks louder than words. Since she join the sorority, its all about the social agenda. Honestly, I think I should end the relationship, because there should be a certain priority and balance. In my case I'm suppose to just accept it and be with her, when she is not being occupied with her social agenda. I don't think so:)