What advice would you give someone leaving a good spouse for ‘no reason’?

This happened with my sister in law. She is known for hopping from man to man, until she married the last one. she's 33.

She comes to my wife and i and says She wants to leave her husband, the father of her kids. He didn’t do anything wrong, he isn't abusive, he is incredibly supportive, loving, does everything she asks, She just doesn't feel the spark any more.

What i said:

Here is how this historically has played out:

1: You leave a good man who did nothing wrong. Mainly due to boredom.
2: You get back on the dating scene, to find a bunch of jerks and probably a couple of abusive and probably drug or alcohol addicted a-holes but hey, they are exciting!…. for about a month. Then the thrill turns to depression or outright horror.
3: You swear to remain single. You do so for a few months.
4: You repeat steps 2 and 3 several times.
5: You make a bunch of posts asking where all the decent stable people are and why you can’t find them and moan about how lonely you are.
6: The rest of us laugh at your clown ass for leaving EXACTLY WHAT YOU ARE NOW ASKING FOR IN THE FIRST PLACE.

Doesn’t matter if its a man leaving a good woman for no reason or a woman leaving a good man for no reason. You reap what you sow and you make the bed you lay in. So if you have any sense, you will do something sane like seeing WHY your feelings have changed. Hormonal changes for example can cause low libido and not being able to enjoy anything like you used to- and there are treatments for it. I am not saying that is the cause, merely pointing out you would be a damn sight smarter to figure out the actual cause before you act a total clown and live to regret it.

Oh and PS: Don’t expect him to be waiting for you or take you back once this has run its course. He won’t. Oh and if he pushes for full custody of your kids, i will support him, fund his lawyer and make sure you lose. I suggested she get into counseling before you do something stupid.

Updates
2 mo
Notice where i said it doesn't matter if its a man or a woman, in the bold paragraph? Id have said nearly the same damn thing if it were a brother in law. Read the whole damn thing before you say something stupid like i am attacking women or something.
Updates
2 mo
Nikki yet again you're gone. You should know better than to insult. No wonder you're not a mod any more.
What advice would you give someone leaving a good spouse for ‘no reason’?
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