If the cheating partner is having fun for now, their happiness will be short lived.
So I can only take from your reply tho, that you think the one cheated upon is the one to (blame) look at themselves.  Funny that.. a bit of a one-way street eh?

You are betrayed, you are responsible. I'll refer you back to the recent post by PZ547, whose comments are worth re-reading.

Are you saying boredom and not getting enough sex  relieves the cheater of any responsibility?. Sounds like it to me.

What about the commitments made in marriage?. Is temporary pleasure , perhaps leading to another relationship,
a sign of a decent person?. 

i couldnt imagine cheating as "fun", thats my problem. All this incognito, skulking around and fear of getting caught that they seem to do. Too much hard work. Maybe im too lazy to cheat.

John Smith wrote on Aug 17^th, 2016 at 4:34pm:

  Boredom creeps into relationships-simple- after many years with the same partner they want a new conquest  new thrill--not rocket science-- it is innately in most men to want to cheat, they have to fight the urge. Given the the opportunity and if they think they wont be found out, they will most likely cheat. Women the same- I am a loyal partner, so I have never cheated, but there are temptations out there and people do cave sometimes.  It doesn't have to be someones fault, boredom is boredom and as for whose fault is it- the one who is married is at fault , it is he/she who stands to lose after all- if looking for fault then that is pointless- if you don't tend the garden of marriage then if the wheels fall off well then - look at yourself no one else.