(* I read your update. It explains a lot. )
Oh good grief! What a crock. I will tell you this- He has thought about this long and hard. Because he has all the details of what he wishes/hopes/wants.
He is either a middle-aged man who is bored and honest, or someone who is clinically going through a real mental/emotional crises, or someone who has ulterior motives and is not telling you the whole story.
have you both sought counseling together?
Then there is this thing: at which point does one become a door-mat and the "martyr" and the having to put up with everything... while the other one gets his fill and fun and whatever he wants.
Then there is your child. How is he/you going to explain all this to her?
Then, there is the VERY real thing where If I were you, I would have HIM tested for STD's every month, and you too. You don't want to catch any sexually transmitted diseases while he is finding himself. And I would want PROOF that he went in for testing.
I'm real sorry for your going through this. Some men, can maturely grow through it with their Spouse. But it seems he does not want to "include" you in all this. But yet does not want to "divorce."
Whatever it may be, you best get all your ducks in a row... and legally ascertain, what EXACTLY does a "separation" mean to him??? And then, how it will affect YOUR custody of your girl... and the ramifications of all that.
Maybe he does not want a divorce because after all, it costs money.. and then alimony too. So, to some, a "separation" is the easier thing, financially, for them.
Get to the bottom line. YOU deserve that much. No pussy-footing around. This impacts YOUR life and your child's.
Bottom-line, he HAS to be responsible for his actions... he is not acting in a bubble with his own dreams... it involves other people. Namely you and his daughter.
If he feels lost and needs to find himself again and experience all the romanticized ideals of a man roaming the earth for enlightenment... then he should do that without harming his family... nor taking their love for granted. Some people have the urge to do in life what they always dreamed of and don't want to pass up anything.... which is fine. But at what cost? He told you he lost his passion for you. But it is probably that he lost his passion for stuff... which he may not even know himself. Or, he has a whole other life planned, separately, and knows it. BUT is not telling you.
YOU have to lay down your boundaries too.
To me, his whole "story" seems like a real crock.
I would not put up with such bull****
Al the best,
Susan