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

You both are on polar opposites of the scale.

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.

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.

A Korean Stuido made Stellar Blade and Japanese stuido is remastering Lollipop Chainsaw. So why are western developers so aginst to cenvtunal female beauty?

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.

So, don't try to compete with them.

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 am still studying engineering. I feel worried being an average student. Can I get a good job in placement, buy a house, and a car? I don't know why I feel this.

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

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.

This happened long or shortly before they physically left.

Why is Reagan seen as the best president in the USA when he literally destroyed the American economy with trickle down system and was strongly against worker unions?

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.

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