As crappy as this may make you feel, it's normal for him to be depressed. He's grieving the loss of OW. You'll just have to let him ride it out.

If you are still hopeful of marriage, just keep DBing. If nothing else, it will make you a better person to have learned the lessons from DB and the people on this forum will give great insight.

Good Luck.

Me-49, H-45
M - 4, Together 9
SS-9
Bomb Dropped - 9/12
Separation - 10/12
Reconcile -2/13
Separation - 8/2013
Reconcile - 10/2013
Separation - 12/2013
Reconcile - 2/14
Separate - 5/14
H Filed D - 8/14