I honestly don't know why people think there's a good, easy, gentle or what-have-you way to ditch or reject people. There's just not, if they care.

If the friendships feel less reciprocal because of something they're doing/not doing, then...honestly, I would not worry this much about it because, to me, it's showing me they don't really care that much. That's not always true, sometimes the person just lacks awareness, but...if I want to end it for some reason that is related to their behavior, then whatever I want to do that works best for me is fair game. There's no point in my working hard to be considerate when they're not giving me what I want/need in a friendship, i.e. they lack some level of consideration towards me.

In any case of events, because I feel/recognize that there's no good way to ditch someone, if it's something like Skype I just stop logging on or don't really respond to their messages on that platform and don't initiate contact. For me to remove someone or block someone, they have to do something pretty bad. I'm also very much a "treat others the way you're treated" kind of person, and it seems like it's just very normal for people to stop responding and ignore people they don't want to communicate with. Even if it has bothered me in the past, I'm not like, "Oh, because this hurt me, I don't want to do it to others." I go by social cues of what seems to be acceptable or the norm, or my own twisted sense of fairness/leveling the playing field (i.e. if I have to experience something bad, I'm going to make others experience it). That's just me, though.

Also, remember that people have their "preferences," so to speak, when it comes to how you reject them, and it differs and there's no way for you to know what someone's preference is without their telling you. So, again, all this thought you're putting into this is kind of pointless just because you have no idea how to hurt these friends the least based on their individual rejection preferences. Personally, I hate all rejection to the point of not doing things that could lead to it, unless I 100% have to (like applying for jobs). Others are fine, as long as you're direct with them. And some others may prefer attempts at being gentle. [shrugs]