My xH has started numerous habits/hobbies that he used to never be interested in (would tease me about some). It used to be frustrating ("Why couldn't he do this back then?" sort of thinking), but it gets easier. Some of the hobbies are great for the kids (he used to never take them out places, now he does), so I try to see that part of it.
And I agree. We didn't fail. I take the blame for my part of the failure of the marriage, but only for the time BEFORE the affair happened. After that, its all on xH. I would have fought to come back from everything, if only I had someone else on my team.