Most Helpful Guy
The worst mistake you can make is to allow a girl to have direct control over your feelings.
Don't appear weak, physically or emotionally. You want her to have that sense of uncertainty where she might anger or displease you. Draw a proverbial line in the sand that she must never cross. Once you have her feeling that way, she's yours. She respects you as an authoritative figure. She respects you as a man. She becomes submissive. That's what you want.
Muscles are kind of a big deal but ultimately it's the mental aspect that will keep her around.