There is a Spiritual principle at work here.
Stated simply "Everything happens for a reason"
All is the result of great planning and much effort on the astral and inner planes where we are intricatly planning this all out, so as to benefite the most people in the most powerfull ways possible.
Can you say that anyone should spend thier whole life here and never leave, that would be silly. You may not like why people seem to leave but is it really necessary for everyone to have a loving reason to exit. Sometimes our own obsessions need some devine intervention to put us on another path. Sometimes we need a good kick in the pants to realize we have beaten our head against the wall long enough. Or maybe we have finally done enough for others and the scale is now balanced. Who can say?
I try to "Give it to Spirit" and accept what people want to do, giving them the total freedom to do that, without assinging blame. Even when fights break out, I try to ask myself "Why do these two need to fight?" Who am I to say it will not bring some greater benefite down the road.
And lastly "Trust in Spirit to provide the expierences we are ready for next" I wish them well on thier path wherever it may take them next.
These principles exist in many so called Religions under different names and they are accepted by most Spiritual paths.
Suck the nectar from the Religions but toss the thorns.