Why do I feel like being with this other guy?

I'm in a serious relationship, And I love the guy to death, but I get this odd sensation to want to be with this other guy...What do I do?

I think its a pretty normal feeling that a lot of girls get in a relationship. ill admit that many times I have had the same feeling as well! but the one thing that I remind myself over and over again is that...Once I get the other guy that I like, would the guy that I like treat me the same as the guy who LOVES me?.. think about that one. and then you have to realize that if things do not go so well with your "new" guy, you cant always go back to the last one. Most guys dont realy forgive and forget that easily if they find out that their girl left them for some other guy. GOOD LUCK!!!