Is this a sign that a guy really must love a girl if she can make him feel like that?
Yes. You gave him a stable, loving relationship so he can deal with past issues. That is very good of you. You sound like you're doing a great job meeting his needs. I want to caution you don't forget to get YOUR needs met. You have to ask him. He is not a mind reader.
First, ask him if he's bored. He may not be.
He calls you a lot each day? That's a good sign. It means he really likes to hear your voice, because he probably feels close to you, though he may not admit it. His actions tell more than his words, though. It sounds like you answer when you can, which is also good. He simply really likes you and since he can't be close to you geographically, he likes to hear your voice. Why not tell him you like to hear HIS voice also?
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
(Please note, we give the best advice we can based on the information given in a post. For better advice, please include the age of all romantic partners.)