But I disagree that she/the others didn't care about Jasper. They clearly did, especially Monty and Bellamy. But Jasper was beyond their help sadly and there was nothing they could do about it but accept his decision ultimately.

Whereas Monty tried and tried, but there was no changing Jasper's mind because the depression had set in too much.

I seriously do not see how else any of them could have helped Jasper further. At some point, only he can help himself ... no one else.