From Quora:

My wife got the benefit of my newfound sexual energy – I started banging the living daylights out of her too. I lost weight, I dressed better, I became more active and I was generally all-around happier. None of it was due to my wife. She was just there to experience it. So in that respect, yeah, maybe it was.

But it made it more difficult to stay in the marriage, to be engaged and interacting with my wife. It’s one thing not to be in love with your wife any more. If she’s not a shrew and she’s a good wife, and she’s fun and nice to be around, then you can make it work. You can be friends who fuck and have a family together. It’s totally tolerable.

But when you love someone else, and that’s where you’d rather be, THAT is when it gets tough and all that good stuff that she was feeling was just window dressing.

And when I lost my affair partner, it was the worst. I was profoundly sad, and I couldn’t tell my wife why. I’m better now, but it is still difficult to try to feel close with my wife. I think my affair took that away from me, and I wonder if there’s a way to get it back. I don’t think I’m over my loss quite yet.