Thanks, dijmart, as I've been going through a breakup with a one-sided friendship and it's good to hear someone agree that it is not a friendship if there's no give and take from both sides. Though I have begun to realize that there are different types of friendships and it comes down to what you want from the relationship. In your case, Annieinside, if you feel good about having someone who trusts you enough to lean on you, even if you can't lean on them, then maybe it is worth it to continue such a friendship, as limited a friendship as it is. It might be nice to have one or two such people in one's life.

However, if such a relationship is draining (as it sounds from your description of all three) and you have your own mental health to deal with, then there is nothing mean about distancing yourself from them or saying no to a plea for help and claiming strict "me-time." If they can't support you in that, then perhaps it is worth letting the relationship(s) dissolve. Your own mental health above all else, as my mom would say. You won't do anyone any good if you get run down by too many demands, so it may be a good time to pick and choose what relationships are worth what amounts of stress. As much as they lean on you now and should appreciate all you do, they should learn to cope without you, imho.