My friend spends every waking moment with his girl friend... is this normal?

My best friend that I have known since I was seven years old has recently come into his first serious relationship. It happens to be with one of my ex girl friends that I had pretty brutal break up with. I’m a little ashamed to say but I resent her a little (stuff she did during the break up) But I’ve just dealt with that because she’s dating my best friend. Since he’s started dating her he spends every moment he has with her if he’s not texting her, or on the phone with her. She’s always the main topic of our conversations and there have been multiple times where he’s ditched out on plans we had, so he can hang out with her, or even just stay on the phone with her. Its had a massive effect on how often I get to see him. I’m just wondering if its normal for a boy in the middle of his teen years to act like this?