I keep hearing that this is frowned upon, but I cannot help it. After I share, I circle back and explain how and why I connected the two stories to try to recenter the other person. Is this annoying? How do you want ND people to respond in that case?
Depends on the similarity of involved emotions (at the moment) and issues, is it one on one or in group (here might be advisable to dodge like 80 percent of the times if you are first to do so) and random stuff.
Usually I'd only share something like that in a one on one setting, I think. And usually after I share I'll say something like "all that to say I really relate to the pain/frustration/sadness and can't imagine blablabla". Would that still be annoying though?
Depends on the thingy in question (and very much on recency/freshness of emotions).
bad
Like say someone pet died, if its like a week ago i would ask about the pet themselves, and their life to let person dump their memories (if they want to that is) and cry and/or give a hug, if it's 2 years ago we can bond over sorrow/rage/whatever. If it's death of family member, highly contingent on their relationship (did they love their parent/grandparent, were they estranged, did they hate them for a time, did they hate them period), if i don't know, more likely i would ask around about that stuff first. Sure i grieve my grandparents and great grandparents, but also they were good people, and i can't truthfully say "i know how you feel" in worse situations. I think, i cautiously ask around in general to gauge distress and kinda go from there (?).
i would only find that annoying if it's a fresh stuff vs old thingy. Even if you do know how they feel, it still rubs the wrong way, if it's recent bad stuff. If it's continuous ongoing vs ongoing stuff, also fine to share, i think.