welcome to the forum.
I think that the best thing you could do is support her. Don't make a big deal out of this. Dysthymia is a little less severe than depression, but it is chronic, so she will have this forever. The best thing she could do is get on medication for it.
As for her boyfriend with depression. If he gets help, he will be fine. Medications and counseling have come a long way, so don't see it as a lost cause. It is hard to understand depression when you don't suffer from it. We can't control how we feel until we learn some coping mechinisms. So have patience with your sister and take this one day at a time. Maybe ask if she wants to talk about
it, but if she doesn't, don't push the issue. Out of sight, out of mind, maybe she would rather not think of it at this time. Just be there for her, that is the best that you can do. And offer suggestions of counseling and going to the doctor for perhaps medications.
She will be the same person, whether she is suffering from depression or not. Don't give up on her, and don't express your negativity of the relationship. Maybe they are good for eachother because they understand what the other is going through. This is not the end of the world. She will be fine with help. Try to encourage her.
Best wishes for a great day.
Moderator-Depression and fibromyalgia
fibromyalgia, Chronic fatigue, depression,allergies