Right!

The law of equivalent exchange!

To obtain something, you must give something of equal value!

What does it have to do with this?

Well... To put it simply,

I used to think that the law of equivalent exchange is an absolute rule that applies to the whole universe.

So whatever I did, I used that law as a basis.

However, Winry, she...

She just flips over the law of equivalent exchange easily like it's the norm.

She easily leaps over my sense of value, again and again,

it's never not astonishing.

I guess that was my deciding factor.