Native speakers of any language are prone to miss this, but a lot of grammar makes no sense! For example, “I must” translates to “〜なければならない” but “I have to” which means the same thing would literally be “〜持つ(possess) へ (to)”. To a Japanese person, it doesn’t makes sense that “must” and “have to” mean the same thing.

So, a lot of times, it’s best just to go with the flow and not to worry about the little things.