Warning Sign: You complained to your girlfriend when she accepted your neighbor’s invitation to work out together. You thought he was disrespecting you by asking her, and it would be awkward for both of you if he got the wrong idea. Plus what if their friends saw them running together? At least you knew she wouldn’t do anything. She’d never jeopardize the future you were planning together over someone like that. She preferred intellectuals, not guys with muscles and tattoos. She would never be the kind of girl who would let a guy fuck her just for a big cock.