First: How he handles small crises. If something goes wrong when you're together, see how he reacts. For example, if you're running late to the movie theatre and when you get there the movie is sold-out, watch his behavior. If he gets huffy, that's OK as long as he gets over it quickly. But if he stays mad for the whole night, and blames you because you took too long to fix your hair that's a problem. A man who really cares about you will be able to work through a crisis with you not against you. You'll be able to agree on a plan B for the evening, and move on.
Another way to size up his love: How he reacts when an old flame calls you. It's OK for a guy to feel a bit jealous when an ex comes calling. But there's a big difference between a fleeting sense of insecurity and a dangerous jealous streak.
If he accuses you of cheating, fights with you or forbids you to see your ex, he's insecure and threatened - which means he doesn't trust you totally. A guy who really cares about you won't doubt you so much.
And a final way to tell how much your man digs you: The way he reacts to your bad day. If you have a horrible day and your guy gets a taste of your bad attitude, see what happens. When he can handle your foul mood without taking it personally, he's tuned into you he knows there's a bigger issue. Also, if he offers to run you a bath or take care of dinner - big bonus points. If he can be there for you and comfort you when you need it most, you can trust that the two of you have one strong connection.