My ex moved on so fast. How can I overcome the pain?

Instead, focus on taking care of, solving and healing what you are experiencing right now.

This happened long or shortly before they physically left.

This is why you can't expect them to feel anything close to what you're feeling right now, because you and them are on a completely different stage in the healing process.

Why wasn't Queen as successful in America as in other countries? Then, after Radio Ga Ga, they couldn't even get into the top 40 in America even when these songs were top 10 hits everywhere else in the world.

On their side, there has been a process of emotionally and mentally checking out while you were still together and while you were under the impression that everything is cool.

And during this process, they either started seeing someone new who they planned to secure as their rebound option or were busy creating their post-breakup plan.

So, don't try to compete with them.

When Trump blames DEI, isn't he just saying "it must be because there's black or brown people involved"?

You both are on polar opposites of the scale.

What they do doesn't matter and it's completely irrelevant to your healing process, though it’s valid to hate and judge them harshly for leaving the way they did.

Simply put, because they have been prepared and you weren't.

Trans athlete embraced as California track and field champion by peers while adult activists duel - San Francisco Chronicle

This is why comparing yourself to them in terms of the healing process isn't going to help you in any way, shape or form.

I.e. you thought that you had the perfect deal whereas they had already made up their mind and just weren't as emotionally invested in it as you were.