F!ck man, the plot thickens as I read onward. I am so guilty of all these same mistakes in my past. The dude my ex fell for was a big f*ckup too in the expat community. You mentioned your ex talking about wanting to have children, settle down, etc., mine did too, had a kid 9 months after she arrived in Paris where we were supposedly going to open a pizzeria with a guy from her hometown in Italy, haha.
She now lives back here in Cambodia with this guy, their daughter, unmarried happily, and they live separate lives while still kind of being in a relationship I guess. I've seen her a few times, but even though it's been more than 10 years, it still cuts like a knife to meet her.
There is always a positive outcome though, I accidentally became fluent in Khmer while we were together, and failed at learning Italian even though I spent hours a day on it. In the end we drifted away, she had a high-paying professional teaching job with the French government while I worked Nigerians and Filipinos in the lowest tier private schools. I hate to admit this experience turned me away from the expat community and sent me fully into the Khmer world for all my social, emotional, love, and conversational interests.
I think that for anyone with some level of conscious and compassion that this always remains the case.
I think that these girls never get past the liking the bad boy phase or at least once they do, it is often too late for them to get a good guy. I believe that this phenomenon is actually quite widespread and well-documented. In the end I feel as though women will suffer more from attempting to extend their youthful crazy times than men will because like someone said in a meme I saw recently, that "the rules change dramatically for men and women past the age of 35."
This may come across as crass but men generally can date women 10 or even 20 years younger than themselves well into their golden years but you almost NEVER see the reverse being the case.
The last thing you mention reminds me of the very few longterm foreign resident ladies here. Most of the ones I know you find it hard to date because the Khmer men are a bit chauvinistic often unfaithful. The foreign guys here are mostly interested in local women, and the foreign guys that are available often come with substance abuse and mental problems, hard life for a foreign lady.