I would say that at first they was very very close - due to them living together
You don't form a band with people you don't like - and if you do it's not long till the band splits - or someone is sacked.
As time went on they stay fairly close - not like in the late 60's early 70's,m and form new friends - get family have kids - and with the amount of touring they did - anyone would get sick of someone else - irrelevant of how close they are, have been or anything.
And then as Fred got ill - they came close again like early in there career - more to a point of protection than anything !!!
My views anyway
back off with your Megaton