how do i really get him at all cost?

I really need help on this one. There is this guy i like so much that is in a 2 year old relationship. I am so sure he's not too happy being in it and i wish to do him a favor by taking him away from the girl. 
I also knows he likes me very much but i think he's finding it difficult to leave as well.
Can i get some help here from experienced sisters?