I agree with morrow there. It is likely he really is busy... partly with his other fuckbuddies. You were a good lay as well, so he kept you in his contact list and even kept in contact for if he would be in the mood for you at a convenient time. But you weren't the best or most convenient choice so he stood you up because he doesn't care enough about you in the end. It is not completely certain it is so of course (what would i know if I never met this people) but this is how it comes across to most people with some common sense.
No way to know other than asking him. Guys aren't always forthcoming with our feelings. Not sure why people are taking an attitude and acting holier than thou about your story.
Yes. Never give time nor pussy to the undeserving. Once upon a time he served a purpose, and even knew how to make you feel special. Now, it's time for him to be past tense.
Something else also occurs to me. My best friend's husband's cousin wanted to fuck me, right? So he takes every conceivable opportunity to hit on me. Fine, but I'm not available at the time. I'm not sure he gets the concept of monogamy, but he is convinced I just need his wife's permission. He hit on me so much it had never occurred to me he might not be single. His wife tracks me down at a party and encourages me to have sex with him. Again, I decline, unavailable at that time. Years pass and I'm free and interested. I let him him know I'm down to fuck, but that I'm also very attracted to his wife, and if that's mutual she's welcome too. We have ridiculous chemistry, and by then, also a strong feiwndship, so of course the sex is off the charts. After a few months of that, we happen to enter into a business relationship as well. Unbeknownst to me, his wife cancelled our affair as soon as we had a contract. She told him not to sleep with me, but she never said anything to me. I missed the transition to sneaking around behind her back, and when she found out I didn't think my friendship with her, nor my business relationship with their family would hold up. My story has a happy ending though. But I wonder about yours. Maybe the girlfriend has changed her mind, and he knows he can't tell you that.