My boyfriends fake skype account

I recently learned that my boyfriend has got a secret skype account, witch sort of piss me off and it also makes me really really currious!
Here's the thing: We've been living together for almost 5 years now, we spend alot of time together, and I know he loves me and that he's not cheating on me. So why would he keep this secret from me? He does not know that I know. I saw it by accident when I walked past him. I didn't really get it untill I searched him up on skype the same day and saw a picture I recognised as his profile picture (not his face obviously). So I knew it was him.
So I've got 3 choices (I think):
a) create my own fake skype account and add him, see what he really is up to.
b) confront him
c) Ignore it

The first thing I thought about was a). This was mostly because of the anger I felt when I found out he's not completely honest with me.
But then I realized what an awfull thing that is to do. So I thought about confronting him about it. But what would that lead to anyway? I believe he's got the right to some privacy, I don't need to know everything right?
but it's going to drive me insane.
So I keep asking myself what the worst thing he could do is. And I'd hate it if I found out that he's flirting with girls online, cybersex etc. For me that is close to cheating.
I don't know what to do. It's driving me crazy. I would also like to know if anyone's got any idea why he would create a false account.