Formerly-Welsh Pat did suffer from very severe depression in the wake of John's death, iirc, and has always been dogged by it.
And of course Hellin's anorexia made for a very touchy relationship between them - I can understand that Pat finds it hard to butt out of Hellin's life; after all, she and Tony have had to step in and rescue her repeatedly (as did Tom, when he nobly took the blame for knocking Moike over when it was pissed Hellin actually driving the car).
I'm with the doom-mongers who predict disaster for the HellRob relationship. I do hope so, as I sincerely loathe Hellin, probably more than everyone else in Ambridge put together. She's one of the most stupendously self-absorbed and bonkers people ever.