>

I mean don't marry a mama's boy is all I can say. It is 99% of the time VERY clear from the start, but many women chose to ignore the signs of a man baby.
I have known women who go into a marriage KNOWING that their man can not (aka doesn't want to) clean up after himself, cook, do laundry or perform any basic life skill, and of course they even have a few kids with those man baby's, and then in the end are doing a surprised pikachu face when their partner doesn't help out.
Spite is a powerful motivator. >

And cocaine’s a hell of a drug. >

I don’t think glow ups are meant as an attempt to get someone back. It’s usually a way to mark a fresh new start and to serve as a confidence boost, which is usually needed after getting your heart broken. >

Plenty of people want to improve their appearance as a way to get their ex to want them back/“show them what they lost”. Of course what you described is the healthier way to go about it. >

I was actually thinking the same as this commenter. I think it depends on the mindset and how you perceive a glow-up. Obviously if it's with the aim of getting an ex back, that's a bit sad, but I don't think that's the overall reason people do glow-ups. >

I agree. It's a part of growing up that some people will never understand. Fact is, nobody gives a shit about you, except you, so do it for yourself. You deserve to be the best version of yourself, for yourself. >

It sort of makes me think of an employer offering you a raise when you put in your notice.  Like why didn't you pay me more before?  You were holding out.
Similarly: why did you not do your glow-up before the relationship ended?  Why Wait? >

Exactly >

I agree. It's embarrassing to send spiteful messages to an ex, and completely validates them leaving you to begin with. >

That's why I take the "high" road.  Literally , I forget about Mr. Whatshisname and move on with being a good me. >

and yet, it works every time >

It doesn’t really achieve anything in my opinion for the reasons I described above. So I disagree. >

I just wanted to say, rejections and break ups were a good thing for me because they forced me to soul search. 
With that said, the world is very shallow when it comes to looks. Please realize that looks matter way more than you think. I would say that it matters as much as your personality >

They can absolutely be a good thing and can motivate people to make real changes. It is absolutely valid. 
Looks are also incredibly important, I agree. If you aren’t physically attracted to your partner, it becomes more of a friendship than a romantic relationship and I think that it is a real issue when people get too comfortable with their partners and forget about that. Not putting in any effort into your appearance while in a relationship can make your partner feel like you’re not even trying. For example, I felt like I wasn’t important to my ex when I would get ready for hours for a date day with him and he would greet me in pajamas. It’s not that I was judging him for wearing pajamas per se, I just felt taken for granted. >

About the letting yourself go thing- 
People in a relationship simply are busier sometimes.A lot of women I know felt like they didn’t have time to invest in themselves as much as they’d like because they were busy working full time and still cleaning up after their significant other like they were a child. They do a majority of the housework despite making just want much if not more than their partners so they simply had no time to go to the gym, invest in a new skill, etc. 
Also most of these types of transformations has a lot less to do with actual body changes and more about outward appearance. How they dress/do their makeup/act/places they go etc. but those things are all significantly different for someone in a relationship anyways. I speak from woman’s perspective but if a girl dressed provocatively and was constantly was out clubbing I’m sure her partner would have a problem with that. So of course when they get dumped they are gonna sex up their wardrobe but that’s also to make themselves feel good. 
Overall who cares? If they wanna get their life together that’s a good thing. Who cares of the motives especially if like you say they don’t work anyways