im so lost.

okay so this dude i work with has been flirting with me hard core lately. normally i ignore it and move on. but lately ive felt so lonely that ive actually been enjoying it. like i actually look forward to seeing him. but the thing is we are both in relationships. i feel like such an awful person. NOTHING HAS EVER HAPPENED BETWEEN US AND NOTHING EVER WILL WHILE WERE IN OUR RELATIONSHIPS. how do i stop this. i like it.