To add one thought that others haven't mentioned, inattentiveness to the early warning signs of volatility in the moods of others can often leave us suddenly surprised when others express emotions such as anger or frustration or irritation.
For me at least -- and I have friends who say the same -- this often leads to codependent people-pleasing behaviour because these emotions and situations catch us off guard and can make us fearful of finding ourselves in such a position. As a result, we might develop a maladaptive pattern of pre-emptive management of the feelings of the people around us, where instead we might just learn to accept being uncomfortable, or develop boundaries around the culpability we accept for the circumstances leading to others' moods. In friends who have had abusive or unsafe childhoods, the maladaptive pattern seems especially pronounced because it's an important part of survival.
What this looked like for me before a butt-ton of therapy is that I felt stressed when anyone around me started to express any negative emotion, but even before then, I was orienting my behaviour to give attention to the more volatile people in my life as a top priority. My task selection wasn't really focused on achieving my goals most times, but on doing things that others wanted--or things I perceived others wanted or needed--in order to make sure their days went well and any potential bad emotion dissipated before it got very strong.
For instance, if my (perfectly loving and kind, but 'normal range of human emotions'-having) wife had a bad day at work, I might come home, make them their favourite meal, make up their bed, and then watch a show with them until they fell asleep.
And on the surface, sounds nice! Sounds like caring! But it's done primarily out of fear, not out of caring. There is caring in there, no doubt in my mind, but it's not the first motivator.
And I've seen this pattern play out in me in different contexts and in different ways... with my wife, with my kids, my parents, and in the community; in hovering, fawning, in leaping to 'be useful'...
I think over time, this sort of behaviour leads to an external focus that does make you feel like your job is to help everyone. Throw in a soupçon of impulsivity and then you're telling strangers in the grocery store that the bouillon cubes they're looking at are on sale at the store across the street.
Therapy's helped. It's such an ingrained pattern for me that I fall back to it and it'll be my life's work to remember that I'd rather act out of true love and kindness rather than fear of discomfort.
I dunno, I think it will end brilliantly.