If he really loves you, he'll probably be able to recall the nerve-racking first time he met your family in great detail. Why? Because he cared about making a good impression and probably thought about it constantly in the weeks leading up to the event. If he really, really loves you, it's possible he even prepared a mental list of conversation topics and paid extra special attention to anything you revealed about them.
Once the first parental meeting is over and done with, he doesn't simply move on with his life as normal. Your family are now part of his life and he genuinely cares about them because you care about them. Even if you have a pretty 'difficult' family, he's going to make the effort because it's important to you and he loves you.