Disappointed by a Few Online Friendships

I've written before about being ghosted by one online friend, which hurt a LOT.

I have another online girlfriend, with whom I've been writing back and forth for a couple years. I would consider us close, but I've noticed that whenever she gets depressed (she has severe periodic depression), she withdraws entirely or if she does write to me, she becomes very self-centered. It becomes all about her, and I honestly cannot stand it.

Does depression make people self-absorbed?

I don't judge at all because I've had my fair share of depression here and there, but I don't recall ever withdrawing from friendships or becoming self-absorbed.

I've also noticed that it tends to be mainly about her even when she's not depressed. I tend to do most of the supporting. Maybe she's just self-absorbed in general?

My main point is that I keep getting disappointed by my online friendships. Not all of course, but a few.

Maybe I should be pickier about my friendships?

It's her turn to write back. Lately, I've been reaching out to her after a few weeks of not talking, even when it's her turn to write next. I've now become hesitant to write her at all. It's just disappointing.