Every few weeks she does make her excuses (tired, not feeling well etc.) and heads off to bed early during which I know that she reads her erotic fiction and sorts herself out with vibrator, so she has some libido.
I doubt that she fancies me, but if I ask she says she does. MH is a possibility, there are background issues with childhood emotional neglect from her mother which surfaced during her PND which might be the reason or at least part of it (i.e. an attachment disorder) but she found facing those issues through counselling too difficult and refuses to try again.
As for a list of why I stay that is many fold. I love her, want her and want to be happy with her is top but we are also best friends and make each other laugh. We do have fun, we do parent well together and we have great kids.
On a selfish basis I would hate to be anything less than in my kid's life every day and even if we co-parented 50:50 that would mean half the time I wasn't.
Financially, we would not be in a position to both afford large enough accommodation to accommodate the children I would most likely have to go into a bedsit or shared house. So 50:50 wouldn't be doable either. I suspect that the DCs would blame me if I left and would side with their mother.
DC1 displays some elements of autism he, dislikes change DC1 & DC2 have exams next year (GCSEs & A' Levels) so It could be disruptive to do anything now, DC2 will be doing A' Levels in Summer 2020, so I wouldn't want to do anything to disrupt daily life until after then.
If I end the marriage chances are I'll also lose my best friend, while I have a reasonably large circle if friends none of them are close and I have no RL support.
She is making an effort, she didn't think that there was anything wrong with a marriage becoming platonic over time, she is slightly baffled that this is "now" an issue despite the fact that I have raised it repeatedly but doesn't want to lose me so she is trying.
As I see it I've put up with things for a while and we're working together on this I'm not prepared to throw in the towel just yet, if I'm still in the friend zone, rather than a husband, once DC2 has done her A' levels then that's got to be time to it to draw an end and move on.