How to use には and では in the sentence

Question

日焼け止めを塗っていれば、そんなことにはならなかっただろうに。

Why did we use には here after こと, what is the meaning? Can anyone explain what is the grammar of には and では

Answer 1

～ + に + なる is a basic set phrase that means "to go ～", "to become ～", "to end up with ～", "to turn out to be ～", etc. This に is roughly an equivalent of English "to".

• 大学生になる to become a university student
• 終わりになる to come to an end
• 元気になる to fee/get better, to recover

こと on its own refers to an event. Here, そんなこと refers to the resulting burnt skin, so it can be translated as "such a result/appearance". そんなこと is marked with に. は after に is a topic/contrast marker used in a negative clause.

Therefore:

日焼け止めを塗っていれば、
If you had put sunscreen on,

そんなことにはならなかっただろうに。
(I suppose) You wouldn't have ended up with such an appearance.