Never feel bad for knowing your limits and acknowledging them. And if anyone tries to make you feel guilty you can tell them to fuck off. They have ZERO clue. If they did they'd understand.
In all the instances you're listing, had you ignored your feelings you wouldn't have been helpful to others - you just aren't in that space. And may never be again. And that's ok too. You're "purpose" may have just been to give the time you did. It never had to be a life long commitment. Do what is best for you, and that applies to moving, dating, counselling, support roles, almost everything. Grieving just isn't the same for all of us.