I think if someone is to the point of not eating/not drinking ... they are too far gone, mentally and emotionally, to derive much "support" for this decision from another human being. Beyond sitting and holding their hand.

You could support them in the way that hospice does. Why not call-in hospice? My first paragraph, Op, was mostly to say I don't think you need to shoulder this. At least, not by yourself. And not uniquely.

And remembering, since she is married, the spouse is always next in line to make care decisions, legally.

This sounds really hard. What does your stepfather think?
I’d personally try to get my parent to a therapist and a psychiatrist, not a “psych nurse.” She’s only just arrived in this new place, it’s winter, if she has any chronic pain it might all seem hopeless. Is she getting physical therapy?
What if anything did she do in the past that she could do now?

At 88 and in her circumstances I'd say go along with whatever she wants. It sounds like her life as she knew it is over or at least it is in her mind. She sees no future for herself that is acceptable. She has stated she wants to die. She is at an age where many of her friends, relatives and acquaintances have died or are dying.

If she doesn't see herself getting better physically or mentally then why would she want to live? I don't think there's anything you can do to fix that other than try to make her days as pleasant as possible by helping her enjoy little daily things if you can. If her life gradually improves in little ways she may change her mind. In the meantime if she really doesn't want to eat or drink then let her. As PP said that might only last a few days before she changes her mind.

It all sounds rough on you and your father but each of us should have the autonomy to make these decisions for ourselves especially if the mind is still sharp and especially if we have been alive already for almost nine decades.

Have you tried a therapist? Seems as if she needs one. Have you tried a diff SSRI? Seems as if she might be able to tolerate one that isn't what she's had before. Or an anti-anxiety?

Have you looked for cancer? That is precipitous weight loss.

She can, of course, take control of her death by not eating. But it isn't that easy to do. A lot of people can do it for a few days and then start to eat again. That said, it can take quite a long time especially if she is drinking water. Even without drinking it can take over a month. It's not a painful way to go though particularly. It's more like a shut down.

Does she have a living will directive? You'll likely need that as well.

My 88-year-old mom was in relatively good health and still in her house until last summer, when she started to lose weight and had constant anxiety and nausea. Many many docs and tests later, we have ruled out a brain tumor, GI problem, ear problem, every possible explanation. In the fall, she had a back injury and she and my stepfather had to move to independent living.

They no longer have to worry about cooking or doing much shopping. She recovered from the back injury and walks with a walker. But she is still miserable. She refuses to go down to the dining room or do any social activities at her independent living place. She no longer complains as much about nausea, but she says she sleeps only 4 hours a night with two Lunestas. She has lost 40 lbs since last June (from 157 to 117 lbs). She says she wants to die. She has been to a psych nurse but the only thing she's on is Lunesta. (She has been prescribed antidepressants, but for several months claimed that every med made her sick, so her chart now says she can't have them.)

My sister and I are ready to give up. I have told her if she wants to stop eating and drinking, I will support her, and we will get hospice into her apartment (even if we have to pay--I don't think a doc will say she has 6 months to live). I have read what this entails (Voluntarily Stop Eating and Drinking (VSED)). It sounds absolutely excruciating for the dying person and their family. It is also so hard to think about helping her do this when mentally, she still seems like her old self at times--still sharp, memory pretty good. But I can also see us reaching a point where we realize this is what she really wants and we all accept it and are at peace.

The only other option I have thought of is to give her some psychedelic drug to try top snap her out of her funk and depression. But I fear this would backfire and it would make her really sick and even more miserable.

Has anybody been in a similar situation, or had a parent without a terminal illness decide to VSED and die? Advice welcome.