Slink Trev's mate Claire says:
I am a strong believer that the opposite sex can be friends with each other and nothing else. But unfortunately we're not always on the same wavelength and sticky situations like yours arise.
If you've found out through someone else that he fancies you, you can only play dumb for so long. It happened to me and I ignored the signs for years. When it eventually all came out (from him) and I said I didn't feel the same, he was actually fine with it. And the relief of getting it off his chest helped him get over it really easily.
To know where I stood was crucial to this, so you need to let your mate know how you feel, so his feelings can move on and your friendship can grow stronger.
If he's said anything to you about his feelings, this should be a good opportunity for you to say: you're a great friend, I cherish you, but my feelings don't go any further than that, and I'm happy with my boyfriend.
However, if he hasn't said anything and it's come from someone else, finding the right time - and the courage - to say something is tricky. I would find a moment where you're chilling out together, get on to the subject of relationships and simply tell him how much your friendship means to you.
Say that someone told you that he might fancy you, and whether this is true or not, you want him to know that your feelings don't go any further than mates and that you hope you're going to be friends for a very long time.
Hopefully this means that he won't have to explain himself, and if he gets embarrassed and pretends that he doesn't know what you're talking about, at least you've been straight with him and he knows where he stands.
Hope it goes well Carmel!
Cx
