Is my boyfriend cheating or about to cheat?

My boyfriend recently went on a medical research trip to Connecticut. And of course like most relationships distance always creates a little tension and can make one another uncomfortable and insecure at times.Today my boyfriend told me that about a week ago this girl was flirting with him and brought up being friends with benefits...i was upset about this for one because he told me a week later and another because he entertained her conversation. He also revealed to me that many girls have been looking at him in attractive ways. And now that we're having tension in our relationship he wants to see more what these girls are about as he told me. He wants to see if these females are willing to give him more than i've given. And from the beginning of our relationship to know i've had issues with guys and some of them trying to get back into my life and some males that didnt want to leave. Thank God I finally got rid of them.There were also times where I fell back on my word but fixed them and made a mends.But he still holds my past against me no matter what I do. I dont have any one to look and see if he's doing any bad or good because i live in Virginia.I've changed some and i am still changing my old ways to knew ways to make our relationship better. But somehow he thinks im "Crying Wolf". I dont want him to go because I know that we are meant to be together and I know that we can work through the frustration that we are going through. Last night i waited for his work out to end and for him to text me after like always. I waited until 10 and finally texted him. When i asked him what time his workout ended he said 645-7. I asked why didnt he text or call. He said because i was tired then and i am tired now. He then said that he was hanging out with his friend. My problem is that he wasnt tired to hang out with someone he barely knows but didnt have the two seconds to send me a text on his way back to his room or while he was hanging out or even call after the work out? Is this cheating behavior or am i being paranoid? Also in the past he has also thought about cheating on me(this was about 2 1/2-3 months ago). Please give good advice I really need that and some encouraging words.I dont want him to go.I love him so much.We've even talked about engagement and he has my ring to get sized.