<human>: So me and my bf have been going out for almost 8 months and it has been the best thing to happen to me this year. We're very close and tell each other everything about anything, especially our relationship with our friends. He has a lot of friends that I have never met but he always tells me about them if I'm curious, well except for one.

There is this girl who he started contacting shortly before we were going out that I know he talks to constantly on facebook and skype. I know nothing about her except that the one tine he told me about her he said that he had a huge crush on her for a long time. but this was before we were going out and I haven't heard anything about her since.

I see him talking to her on facebook pretty much every time he gets on. He also talks to her on skype and I've seen him texting her a few times before, but every time I glance at their conversations he'll quickly close out the text or change the tab so I don't see what they are saying. Even on his youtube page he's liked and commented on every video she's uploaded. His friends even mentioned things him and her have talked about that I've never heard of before.

I really want to feel like I'm just being paranoid, and maybe I am, but why would he try to hide a relationship with somebody he is obviously very close with? He always tells me everything that has to do with his life so why would he try to pretend like this girl doesn't exist when I'm around when he seems to tell his friends more about her than his own girlfriend?

Also I haven't mentioned this to him because I don't want to come off as accusing but should I? And does this sound like cheating? If not why would he act like this? Please help me out here.

Can you summarize the given text in a few sentences?
<bot>: My bf tells me everything but hides a relationship he has with a girl he used to have a thing for. And all of his friends seems to know except me, is he cheating or am I paranoid?