kpop, you're entitled to your opinion but so am I, and in my opinion this is really bad advice. There's a difference between "shacking up" and living in a "commited relationship". By my definition "shacking up" is a temporary situation while "commited relationship" is the same as marriage but without the liscense. For reasons I won't go into here I lived in a commited relationship with my wife for 12 years before we were married and there's no way this was the same as shacking up. That did happen but it was prior to our decision to move in together and make our relationship permanent. I read the sentence below from walsh's post and applied my definition and to me this reads as "a commited relationship";
"and recently moved with a boyfriend that i have been long distance with.. and we moved in together got our own place."
Especially note the phrase "we moved in together got our own place." So your advice to walsh is to lower her expectations and move out when she doesn't even know if the guy has actually done anything wrong??? Marriage does not exclude adultery so if he is cheating, he could (and probably would) do the same thing with or without being married.
walsh, if you're reading this, you felt enough for each other to move in together and have a commited relationship so I'll repeat my prior advice;
"If you can't bring yourself to trust this guy until you actually catch him cheating I suggest you leave rather than continue to torture yourself" and "if he is actually seeing another girl you will find out soon enough".
Don't just act on suspicion and emotion, give the guy a chance.