The only constant is that things change.
Any given human being is capable of anything at a given time.
We are the worst judges of gauging the effects we have on other people.
A cellphone analogy has given me a lot of comfort. I know that sounds weird. But I had a friendship with someone a while back, lost contact, and years later looked them up and sent a "hello, it's me" message.
The answer wasn't what I expected. It was on the order of, "What are you doing? Why are you following me?" I said, no, I wasn't, but gosh, I don't want you to feel bothered, and you won't hear from me again. Yeesh.
Still, I really admired that person, and their image and our former friendship (and pretty casual friendship is all I'm talking about) springs to mind from time to time. The cellphone analogy: Their mental image come up, and I swipe it off the mind. Seriously, I just imagine me taking that mind's-eye image and sliding it off to the side, out of sight.
It doesn't really give me answers, but sometimes answers aren't there, and that's okay too. It does help me move on.