It's okay to compare spouses' actions in MLC...but remember that each person is very unqiue, has a unique personality and also the childhoods are different, so they may react/behave differently.
In your case, maybe you aren't pressuring him to shape up and do the right thing all of the time...thus, he's not quite as nasty as your friend's h is towards her. I have found that the more you pressure them to come home, drop the OP or pressure them to know where they ae in their thoughts of separation/divorce, the more they will strike out. Guilt plays a role and maybe your h isn't feeling so guilty at the moment.
Well, I don't agree w/what your friend's friend said because it doesn't matter if your marriage was 100% great or 50/50% great. MLC is based largely on unresolved childhood issues and the lack of coping skills, as well as navigating the growing/maturing spurts that they should have navigated along the way. Keep in mind, priests and nuns can have MLCs too. So, it's not just based on being married or living w/someone...
Dig deeper for patience and keep your focus on you and your family and moving forward.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.