Should I be worried?

My boyfriend and I are long distance and freshman in college. We met the spring of our senior year in high school and got to know each other over the summer. We talked all first semester of college and then began dating over winter break. He goes to a school in Ohio while I’m at a school in Kansas. During the second semester he met a lot of new friends and I’m happy for him because that’s what he really wanted. However, the person he has become closest with is a girl. They talk everyday even when he came and visited me because he had a volleyball tournament at my school. Also, they hang out pretty much every weekend in a group, but this last week has been his finals week and he has hung out with her by himself pretty much everyday until 4 in the morning.

Hey, I'm assuming hes told you about her, so I don't think there is anything to worry about. It sounds like he's testing you and wants to see your reaction but there'd was something going on between them, then he wouldn't be telling you. I do unstand how you feel (I realise America is huge distance wise compared to the uk) my bf goes to uni five hours away and it def does test your relationship on all levels. I'm going to uni next yr but chosen one close to home and not live on halls. He's a lot more sociable then me and likes to befriend most people, where as I prefer smaller groups. He has friends who are girls and he was close with one when he first started last year , they went to the gym together etc. I was worried at bit worried at first because she was always there when I went to visit him. This doesn't mean don't ignore it, just keep an eye on it and if something is really bothering you, making you feel anxious then tell him, the first thing he should do is reassure you. The warning sign is if he gets really angry and defensive.

Update: I know this information from a friend you goes to the same school as my boyfriend. He has mentioned this girl to me, so he is not hiding her, but has not told me fully about the closeness of their relationship. My friend has confirmed that when they hang out until early in the morning nothing bad is happening, neither would ever cross a line while I am in the picture based on both their personalities.