First of all it’s completely understandable for you to feel frustrated and stressed in a situation like this. You really don’t have the power to fix other people’s problems. Have you ever been to a therapist? The one constant among good therapists is that they don’t give you advice. They don’t tell you what to do. And they don’t try to fix the problems in your life. But they do end up helping you. So what do they know that the rest of us don’t? They know that the best way to help someone is to listen supportively, to validate their feelings, and to give them a chance to think about their life while leaning on the emotional support of someone who cares about them. There’s more but that’s a good start. And if you can do that you really are helping a lot more than you think.

Take as an example, a conversation I had with my wife today (remembered as well as I can). She was in a really bad mood and wasn’t talking with me.
I asked her “what’s got you feeling down today?”
She angrily said she didn’t want to talk with me about it because she knew what I would say and she didn’t want to hear it.
(That, by the way, is a pretty clear hint that someone is not in present time emotionally.)
I said “so you’re saying I’m never supportive of you when you’re upset?”
She said “I’m feeling overworked and stressed. There’s always too much to do. And I know you are just going to say you also have too much to do.”
I said “I did say ‘I feel the same way’ once when you said you could use a day off. But that doesn’t mean I can’t appreciate that you’re overworked. I understand. There’s a lot going on right now and it’s hard to keep up.”
She continued talking about how she felt. I continued validating her feelings. And she cheered up and her mood improved.

My point is, “just being there” is code for listening supportively, validating someone’s feelings, and helping them regain the balance they need to address their problems themselves.

Edit: to be clear, I’m no saint. Sometimes I’m the grumpy one and my wife is the paitent one. It works both ways.

Suck it up and don’t stand in their way, let them do what’s necessary and mind your own business. That would be my adwise to someone who seems to have the problem to realize that they are not the center of the universe.

I see it at work all the time people thinking that the whole company depends on them and that if they would to resign it would go down. It never does, because once they don’t sit in that spot finally other people can raise to the occasion and do even a better job.

The serenity prayer can help set your course. You don’t have to be religious to understand it and use it as a tool for your life.

God, Grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference.

I had several more paragraphs to say, but I deleted them. The prayer says it all, if you just sit with it for a while.