Well you could make up millions of rules for "fuck buddy" relationship. As for me I follow the "Fuck Yes" rule. I love it, it works, it's fumn and "Fuck Yes" I want it. Nothing wrong with texting me when you suddenly feel that you would like to have sex. You can assume that I also would like to slide my dick into your pussy. Unfortunately most of us have to work for money and haven't quite worked out how achieve it that money works for us. And this means that we are stuck in offices, meetings, business trips, report writing, developing and .... and .... or we need a good night sleep just to shake the fatigue of to be of any use to you between the sheets. If a fuck buddy relationship does not work for you then you will try to find another fuck buddy.
Maybe he had other fuck buddies. I had a female fuck buddy. We used to talk about the other guys she was fucking after we finished. So for me, being a fuck buddy meant we were both available. For this friend, i was a once a month fuck. We lived in different towns ans could only get together on my monthly business trip. You might just be his Monday buddy. Also..rather than hitting him with the "fuck me right now" try to schedule another day of the week to be your turn again. And have him talk to you about the other women he fucks. That woul make you his best fuck buddy