My idiot H tells me last night....I was "TRAPPED"
ohyeshedid I don't know your story specifically and I'm going against the grain here, but I believe that can be true. That could be part of keeping it going. Not the only reason of course, but one of them.
If someone helps me bury a body or drive the getaway car, I'd want to keep the OP quiet/happy. I pretty much f'ed myself with the crime itself but even more so by having an accomplice/witness to that crime. There comes a time when a WS realizes if they weren't screwed before they definitely are now. Some feel this before dday and some don't.
Or is this another HUGE character flaw
Conflict avoidance is common for WS. I'd say almost a prerequisite. Someone who is able to face conflict head on is not as likely to find themselves in an affair in the first place. This character flaw can get them into an affair, because Instead of being mature and talking to their spouse about conflicts and relationship issues (which every relationship has), eventually they feel trapped in their marriage, life, whatever, and feel a need for an easy escape. It's of their own making, but they can't see that. Most definitely CA can keep them in an affair long after the thoughts of getting out cross their mind. That character flaw is going to follow them wherever they go.
Does your husband saying that mean he's snowing you? IDK. Does that mean you should feel sorry for him? HELL NO. But if he is a conflict avoider, and stays that way, he will continue to be an escape artist and act like a victim -- not a healthy ideal relationship partner.
Long before he felt trapped by his AP he made the decision to cheat was an acceptable option. Asking why he kept it going is not the same as how he got to that starting point in the first place. You are going to hear a lot of stuff you don't want to hear. Frustrating and hurtful stuff.
When your husband digs into why and finds things like conflict avoidance, ideally he will recognize it was a problem and do something to correct that moving forward. If you want to R, you want him to figure this stuff out and change it and if he doesn't, you decide from there.