My girlfriends personality has changed, what should i do? (please help, this problem is destroying me)?

Sorry for it being long but please bare with me. We have been going out for 9months now and for such a long time we knew we were right together and were so deeply in love. It is a long distance relationship but i always manage to come visit her every weekend to see how she is even with the comittments we have. In the past she has always been v insecure and shy in her personality and ive always tried to get her past her problems and she has overall become a much stronger girl becoming more socially active whilst we were together. With her getting more sociable had led to some consequences cos now alot of her new guy friends hav a likin to her and she even admitted to me once that she too had developed a liking to one of them which i was v devastated by, we worked things out after a long nights talk and she insists that theyre only friends to her. After that issue she has been more distant towards me, were not as lovey dovey anymore, she doesnt seem motivated to talk to me as before she acts more cold than her past cheery self always wanting to be with me (we used to text practically all day non-stop) and her frequently mentioning her hanging with her guy friends makes me feel so uncomfortable sometimes, like i was texting her an hr ago and she said she was sleeping on one of her guy friends arm then when she said he left i wanted to talk to her more but she said she wanted to head off to bed cos she didnt feel well. I dunno if shes avoiding me and trying to wind me up or something but this problem is killing me on the inside cos shes my 1st true gf, the perfect girl i had been searchin for but now doesnt seem as much now that shes found that there are guys better than me out there and she is a beautiful girl as for me im just average. im planning to call her when she wakes up later today just to get things straight and if worst comes to worst a split up is an option ive been thinkin for awhile now... should i be direct and say things exactly the way i feel and hopefully she will understand? im so confused right now i just dont know how to approach this anymore