I tried to bite my tongue here, especially when the cavalry arrived given that it's very easy to sound defensive but let me just make a couple of observations:
First, how on earth anyone could read the OP and come away thinking "this person is too optimistic" is pretty darned strange to me.
I wrote the post BECAUSE I could see the possibility of a negative outcome and I get replies telling me, essentially, "of course you are going to get a negative outcome"
The idea here is just to say "man it hurts" not to be told I'm somehow deluded. One can EASILY "plan for the worst" on an intellectual basis and STILL say "damn it hurts" when the worst happens.
It's not that "plan for the worst" is bad advice - on the contrary it's EXCELLENT advice. The problem is, when a friend comes to you and says "this thing (whatever it is) is tearing me up inside" that's NOT the time when you start proving how you have all the right answers. They didn't come asking for answers.
I sometimes think that some of us (myself included on some occasions perhaps) are so bound up in showing how many answers we know that we throw them out even when there's no question.
Second, the object in my chosen method of handling my relationship is to keep as many options open as long as possible. I don't think I'm the only one who's ever made a decision before I had to and then found out later that doing so had foreclosed an alternative that in hindsight would have worked out better.
I don't see why (good) advice like "be ready for the worst" necessarily translates to "run headlong and embrace the worst option as fast as you can"
Even if I'm going to arrive at an outcome I don't like, there are still alternatives ways to reach that conclusion
(to wit: one can be divorced from a person who remains your friend and be on good terms as co-operating parners in the parenting job - OR one can be totally alienated from an ex who hates you and both are a source of years of anger and bitterness for the other...even though the divorce is the "bad outcome" it doesn't have to be the "worst" divorce either)
Haste to accept the "inevitability" of the separation will almost certainly make things worse. IMHO.