Is "professionnal relation" the key to longevity ?

I notice that the groups with the longest longevity are the one who seem to have only a Professional relationship

Like in Suju, some of the members are still awkward around each other like leeteuk and Heechul, but their groups have one of the best longevity, you can still see their members everywhere on tv, their sales are still good, and they make recurrent comeback

also in Big bang, the members always said that they have a profesionnal relation but the group is working really well like it is

Same for shinwha, they don't have a "close frienship bond " but they are still active and making activities together often

Quote from chat-2

Aren't GD, Taeyang and T.O.P. childhood friends?

I don't know but i remember that there was an interview few years ago about them saying that they don't really hang out together when they aren't working etc...

and that they usually see other when they need to promote or work on project