The bottom line is definitely that you are not their priority. There's no logical reason my friend waited 6 weeks to email me, to tell me in that email she can't call me. She just didn't want to call me.

I disagree with you that I need to ease up on my expectations. 6 weeks is just rude to wait to get in touch with someone. 6 days is not as big of a deal as 6 weeks. The fact that my friend emailed me instead of called also is very telling about how low on her priority list my friendship is.

I think my expectations are reasonable actually; If I call/email/text/message you, I expect you to respond within a reasonable amount of time. If you don't, it comes across disrespectful and rude to me. When I lived abroad, my friends knew in advance that they would receive letters from me and phone calls since email didn't exist. I always stayed in touch with my friends; I called them every weekend on the dot, despite the time-zone difference and if they weren't home I left them a voicemail.

I made time for those people, when I lived in a different country. And I had a full schedule of work and other activities going on. But that didn't prevent me from keeping my promises to my friends.

My friend lives in the same country and she can't be bothered to return my phone call? Then she sends me an email with the subject line "Ugh, I owe you a phone call" as if that justifies her silence for 6 weeks, despite us being Facebook friends?

No, they're not too busy to respect another person's time and feelings. They're not busy. They're just being a bad friend/relative. My friend could have made the time to call me back, because a phone call takes 5 minutes. No one is that busy. No one.