Search Results: how do you know when i a guy is serious about you

A guy I work with that I have known for years and I have always had a playful relationship. We banter, joke and pick on each other during breaks. He and I started a casual fling with the understanding it wouldn't be a serious thing and that it had to end if feelings were attached. So, we go on this way for months, never hanging out outside of work except for hook ups. Feelings grow. He acts jealous when I talk to other guys, he goes out of his way to make me jealous. He lights up when I walk into a room, this warm, glowing smile on his face. He goes out of his way to look out for me, and a couple of times he says love you to me as we get off the phone, quietly like he wants to make sure I cannot hear. He goes through days where he burns super hot and cold, nervous and jittery around me. When I first say it back finally, he seems happy or giddy about it. I say it a few times, only as we get off the phone. The last time, he seems nervous, and does something to intentionally make me jealous afterwards. I get up the courage to ask him if it bothers him that I told him I love him. He asks me why, and when I won't tell him right away he says I shouldn't and flips it on me, saying what we have was supposed to be casual and why did I allow myself to catch feelings? He keeps asking why I love him but then apologizes and says I don't owe him an explanation. I finally ask him if he feels the same and he says no, that he's sorry he led me to believe he did.