Meh. If original cheating is a plot point or some kind of catalyst - it's alright. Like the early one - it's justified.
The one with Leon is premature and is lacking buildup, imo.
As far as NTR(hell, not even NTR, but most of the stories written in here) goes - 8 out of 10 are just pure garbage.
NTR or not, the main catalyst is "Ohmagad I've seen the penis while he was showering".
I don't know what kind of women some of the lads hang around, but haven't met one who was like "yeah, dick is the ultimate decision-maker".