Have you ever been in a heated debate/argument or suggested you break it off-- and he started to cry?
A guy that gets emotional over you shows he has very deep rooted feelings for you. If your words have brought him to an emotional state (especially if he never cries) -- this is an indication that he holds you and your opinion in high regard.
A guy that expresses his emotions in front of you trusts you and a guy who is serious about you sticks around during these emotional/painful/difficult times.
Don't harm him with your tongue
When you hurt your man you are hurting your relationship! Be careful with the words you choose -- do not be carelessly putting him down or threatening to leave. Although you can say you are sorry, it still leaves a dent and mistrust in the relationship.
Bad boys don't cry
If you are dating a man who has been through a lot of relationships and been through plenty of breakups -- if you are "just another girl" to him , you won't find him crying over you. Any disagreements will have him making his plans for the next woman.
Use hard times to grow closer together
What's interesting is that when your relationship hits a snag, you can actually use this tough time to talk about how you care about him and express that indeed you will make it through these tough times.