Just remember you only hear his side of the story.
Our friend told us he really tried too.
He really tried to seek other women and while yes there were issues on her side too, the main one was his not putting effort into the relationship and making her paranoid and feel unloved.
It was only after hearing his 'i tried' side many many times and believing it (he sounded very sincere and not the scumbag we now know him to be) that we knew hers.
The coward tried to deny it, but eventually the truth caught up.
The only thing you know for sure that your friend has tried is to seek out an OW.
He would be a better dad to separate from his wife and treat her and his children fairly.
How much will this impact on his wife's self esteem and how much will it hurt her and turn her world upside down to learn he is cheating? (which will impact on the kids)
Far less than if they separated or arranged an open marriage.
Plus he puts her at risk if he starts sleeping around too.