My fiancee's guyfriend

I am normally not a jealous guy, I never get worried or jealous if my fiancee is with her friends and a guy, or if she talks to a guy. I believe it's her choice who she spends her time with, I like seeing her happy, and I completely trust her... or do I?
For the past 10 days or so, I have been unable to contact her alot. During this period of time, her friend has jumped all over her. He's always calling her up, giving her sex tips and telling her stuff like "I care about you, and I want you happy." He looks like a player, since he sleeps around alot, but doesn't believe in having a serious relationship. Infact just last friday, he was going to pick her up at 7pm to take her to a concert downtown. I can't decide if this is my head or not.