Intense pressure in the abdomen.

If he flirts, you catch him starin at you, he wants to do what you do, go where u go things like that

You can tell by the way they act around you - Plus most will let you know

Sometimes you can tell by the look in his eyes. The way he kisses you, that he hangs on to every word you say. He would rather be with you, instead of being with his friends. He brings you home to meet his parents, takes you around his friends. Will watch a chick flick with you and not complain once or say anything sarcastic. Catch him talking to one of his friends and he says wow this girl might be the one! Im Crazy About her. Talks about future plans , for instance hey next summer we really should go on a trip down to san Diego, isent that where you said you liked. Smiles and says, you know at the restraunt tonight I caught the guys sitting in the corner boothe eyeing you, and I thought to myself yeah shes with me !! Never critizes you and he says that there is know place he would rather be or do than to be with you.Tells you he likes your parents,when you know he felt like he was on exhibit, goes clothes shopping with you and helps you pick out clothes. Calls you first or leaves a note on your car as he leaves your house and it says on a napkin from a fast food place. "HEY HAVE A GOOD DAY AT WORK" and I just cant stop thinking about you. I think that shows he is into you.

He'll very often tell you.