<human>: Can you succinctly summarize the text in 1-3 sentences?

So I've (20/F) been in a happy, healthy, long distance relationship with a guy (25/M) for about a year and a couple months. Everything's been going great, and we haven't had any real problems. 

Until I found out that he cheated on his first girlfriend of five years with his last girlfriend. Now i've always been one to really value loyalty in relationships, and so the idea that he cheated because "he didn't see it going anywhere" really bothered me. In addition, he's always professed that cheating is a big no-no. Which is why i didn't really understand why he did it in the first place. 

That being said, I've been a little wary ever since then. Knowing that he's cheated on someone he dated for five years has put a strain on my trust with him. He hasn't done anything that would break my trust, but I'm just feeling a bit insecure. He has a lot of pretty female friends/co-workers, and I just feel a bit wary. Is this normal?
<bot>: In a long distance relationship, and I find out my SO has cheated in the past, and has several pretty female co-workers that he talks to a lot. Is it normal to feel insecure?