Wonder - I've told this story before - that my H had a brief affair early in our marriage - I took him back but he never really worked out why he did it. 18 years later, when he had his depression/MLC/affair - my kids were devastated. And I felt SO guilty - because they were in this situation, in part, because I had stuck my head in the sand and charged ahead, having children with my H without questioning harder whether he was a good risk. I'd taken that risk - but my kids were having to pay the price.
Thank goodness things have worked out well for us - but they so easily might not have. I think the valiant things people do here to save their marriages are awe-inspiring - and when children are involved, I think you should pull out all the stops. But often my answers are different for yuoung couples who don't have kids yet but plan to have them in the future.