My boyfriend treats me perfectly, but I have started to have feelings for someone else that I can't avoid... Advice?

I’m 18, and in september 2010 I moved a couple of hours away from home to go to University in London. My boyfriend lives back home, and I’ve been with him for a year and a half. He’s stuck with me through the worst points in my life (my cousin diagnosed with anorexia), and I’ve stuck with him through his (his father died recently). We’ve managed to work it through despite this and the distance, and I still see him usually every couple of weeks at the weekend, the max we have gone is a month without seeing each other.
As well as this, he treats me perfectly, and I mean perfectly. I trust him completely, and the way he acts towards me makes me feel as though I am the complete world to him. I am never embarrassed in front of him, and I could look completely disgusting (like waking up in the morning after a night out) and he would look at me as if I were the most beautiful sight he had ever seen.
Sounds like I’m sorted for life, doesn’t it? And I would be a mad woman to risk any of the relationship, right? But here’s the thing…
No matter what he does, no matter how hard he tries he just can’t make me happy, and that’s all he ever tries to do. Everything’s there, but something’s missing. Because all I ever am is confused, constantly trying to figure out what my feelings for him actually are. I love him completely, but I just don’t know if I’m ‘IN love with him’.
And yes, there is the more serious problem. At university, I am constantly surrounded by men – It’s just worked out the way. In my flat it’s very male orientated. And my course is the same too. One of my flat-mates is on the same course as me as well, so we naturally spend a lot of time together. But none of this had been a problem until recently, because I wasn’t even considering being with anybody else – I didn’t want to consider that.
But for the last couple of times I’ve been out socialising there’s been this one man who’s on my course who I hadn’t had much to do with before (the seen and heard of but not talked to) who I suddenly have ‘clicked’ with. As in we start talking, and we literally can’t stop… Conversation just flows so easily and naturally. And even though we’ve only met properly twice, it feels like we have known each other for years. I haven’t stopped thinking about him ever since we first met, and when I saw him the second time I have been thinking about him even more. When I see him my heart pounds, and all I want to do is talk to him and be with him. And I can honestly say, I’ve never felt like this about anyone before, not even my boyfriend – at any point. And my flatmates realised this connection, like when we were out one of them whispered in my ear ‘that guy is completely into you’. It has been the one time in my life when I have actually regretted not being single.
But now that these feelings have suddenly came about, I am obviously thinking – what the hell is wrong with me? Is this just a crush that will blow over soon? Does the fact that I’m even considering being with someone else mean that I should end it with my boyfriend?
I feel sick about myself… I feel completely ungrateful about what I have… I know that the way my boyfriend treats me is what some women spend years searching for. I know that I’ve only met this other guy twice… And so how can I possibly risk my relationship for that?
I would never ever cheat no matter how I felt about someone, so it’s definitely a case of either splitting with my boyfriend and moving on, or trying harder with the relationship I’m in already. To make matters worse, the flatmate who is on my course also, who I spend literally all my time with, hinted to me the other night that he had some sort of feelings for me too. Which has just confused me even more!
What on earth should I do??? Anyone’s help would be appreciated.