My xh and I tried sharing the house and an apartment, whomever had custody of the children would stay at the house and the other at an apartment we rented. He first brought it up because we could rent a smaller/cheaper apartment and I thought it would be good for the kids, thinking that if we got back together it would have been less traumatic for the kids and if we split it would be a more gradual transition. I think it was better for the kids, but it put the nails in our relationship's coffin, letting him have his cake and eat it too. He could come over for dinner, put the kids to bed and then leave to work on his new R, his EA. It did not put the reality of the situation in his face during a time when he was trying to figure things out.
I don't mean to be harsh, but she probably is having an EA. My xh was and I refused to believe it because he was around all the time, he wasn't really ever unaccounted for. Expect for all the time he was at work, except for when he was training for his marathon and except for traveling for work. It's not just staying out late. I later got phone logs and they talked in the morning on the way to work, multiple times during the day, on the way home and then after the kids went to bed, regardless of which house he was at. He'd do his fatherly duty and then rush off to work on creating a new life for himself. I simply refused to knowledge that that could be happening. Things would have been a lot different had I known.
They got married on Thanksgiving.
Affairs, ESPECIALLY emotional affairs, change everything.
Lastly, while I love FB, my sister was recently served divorce papers from her husband of 28 years. About a year ago he reconnected with his high-school girlfriend and they began an affair. They have both left their respective spouses and are planning on being together forever.
Good luck to you. Fight the good fight!
Me: 42/H: 37 T: 10 years/M: 8 D9, S8 Bomb: 7.23.07 Separated: 1.20.08 D Final 3.19.09 Affair started in '05, found out parts in 11/07. They married 11.26.09