I just want to second what some others have said, because I think that there have been too many dump-hims, too. I really don’t get it. He sounds like a great guy to me—no one’s ever told me they only want me.
Also, you guys sound like you have talked about this. So what of his answer wasn’t satisfactory? Don’t you believe him when he tells you that yes, he has a very close friend, and yes, you’re his girlfriend, and yes the two of you are very different in his life?
If you do need to talk to him, then do. But like some have suggested, don’t make it accusatory or presumptuous, because both of those will only lead to a natural defensiveness on his part, no matter how nicely you phrase it. Keep it open, keep it as asking, not as verifying something (that more likely than not isn’t even there.)
This reminds me of a discussion I had in Poetry Lit—just today, actually. We were reading a beat poem, and at the end one man asks the other for a kiss and is denied. Quite a few people tried to argue that the man was gay. The rest of the poem was asexual, but because they couldn’t see the kiss as anything other than a sexual desire, they were sure that the main character had to be wanting some sex. (This poem, truly, had nothing to do with sex.)
We started then talking about whether or not a kiss has to be sexual: can you kiss someone just because you care about them, just because you’re happy, just because they’re there, and that’s all it means?
There was a strong, small but strong, part of the group that felt like a kiss was a precursor to sex, and could be nothing else.
It was brought up that guys can kiss girls and it not be considered sexual, and even girls can kiss girls and it not be considered sexual. (We did agree that, if the tongue was involved, it was heated.) Family members kiss, and it doesn’t mean incest. In all these cases, it’s just a greeting, or a farewell, or a celebration. So why the double standard?
I’m telling this story here, because, I don’t think it’s all that different. The details are, for sure, hugely different. It’s not two male characters in a poem, it’s two long-time opposite-sex friends; they’re not kissing, they’re telling each other they love each other. But in the general sense, identical.
Like kissing, ‘I love you,’ has many different meanings, and just one of those is sexual. Everyone here saying he’s cheating on you is denying that an action can have more than one meaning behind it.
That he hasn’t told you “I love you” yet doesn’t mean he isn’t getting there. The love you guys are developing in your relationship is different in type, but similar in that it will take time to grow.
—how long has he known this friend, again? Now, that’s not something to feel bad about.
You two are together now, in a romantic relationship, but in the budding of it. Enjoy the development, the getting to know each other at a deeper and deeper level. Don’t expect everything to happen at once, and because it’s not going to. And anyway, that would be dull and fairly meaningless.
As to the jealousy—like others have said, it’s seated somewhere near insecurity/lack of trust in the relationship. There’s nothing wrong with that, but you’re going to have to work on it, hon, if you want this relationship to continue. Without trust, there is no relationship.