The (aparently) thin line between being pushy and a stalker

So, for you guys it may be difficult to understand girls, but I think that there are some of you for whom the concept of being a STALKER might be blurry.
Like the experience I had yesterday, so I'm studying a degree and I have to work in groups, my group is composed of two guys. I along with them, they're nice- that's it- considering that we only talk about things like business strategy, key performance indicators, etc.
Considering that I only see them for an hour once a week I would say I barely know their names.
But...to one of them aparently I'm the love of his life, OH MY GOD!
From out of nowhere he tells me that he is thinking about leaving his girlfriend for me...
So the story begins a few weeks ago, when I noticed him strangely "nice to me", I tried to back away as soon as possible, sensing that something weird might be going through his mind...
But one day, in the msn messenger, he confessed that he is thinking that i'm beautiful, interesting and independenent, and that he could leave his girlfriend for me if I WANTED TO :O
In my state of shock I tried to blow him away by telling him that he might be confused, because he doesn't know me well enough to be in love!!! And to every statement I logically made, he ilogically responded hahaha, he said that he doesn't need to know me more, because in every word he can see the beauty in me (cheesy much???).
After that he said that knowing me was one of the best things that happened in his life (hello? I don't remember your last name). And that he knew his feelings were true because he meets girls every day and no one made him doubt about his relationship (awww sweet, I'm good enough to make yout think about cheating)
And he said that he would never had the courage to tell me that he liked me (or loved me??) in person (but you have the courage to make a fool out of yourself after I say I think you're uninteresting and I don't like you a 10000 times)
I told him NO like 5 times and he always had a stupid answer.
So I ask: Is there a weird group of guys that think that if you tell a woman that you like her and she says no, maybe after 10 times of saying the same she'll say yes?
Is there a support group of all these anoying guys?
Do they Google their "romantic" lines?
Do they think we believe them?
I had to stop that conversation abruptly, because after half an hour of the same he didn't give up, I even told him that I tought that guys only told you that they liked you out of the blue in highschool, ALL THE INSULTS AND SARCASMS MADE HIM LIKE ME MORE, he said that I was special because I was independent and strong (I'm strong and trying to insult you here!) So I signed out before I had him infront of my house with signs saying: I LOVE YOU, PLEASE SAY YES :P