I tried telling him this,
Know the signs of when your girl is breaking bad and don't hesitate to leave.
If you see things changing that you don't like, then speak in it once. If she refuses to acknowledge or correct her ways, then leave. See, women just don't get up and leave men. They have to emotionally disconnect first. If you leave her during the period she is emotionally disconnecting, she will be a nervous wreck. Don't wait until she is no longer attached to you to try to make an ultimatum. By then she'll probably have another dude lined up and don't even care. Strike when you see the changes. The most common changes are:
1. Her routine in how she calls/texts changes
2. She spends more time with other people
3. The way she speaks to you changes (stops saying I love you, no more pet names baby, etc.)
Check all of this stuff. And if she continues after she's been checked. Dump her immediately. If you stick around, she's most likely going to lose interest, lose respect, keep you around for a little bit and then discard you.
If your woman isn't thrilled to see you, hear from you, or spend time with you, clean cut that chick. Your time is a privilege that other women would love.