~てしまう — to end up doing, to completely do, to do something regrettably
This grammar pattern attaches to verbs and expresses either completion of an action or a sense of regret about something that happened unintentionally or unfortunately. It often conveys that something was done completely, or that the speaker feels sorry about the result.
Example: 大切な写真を間違えて消してしまった。
I accidentally deleted an important photo.
大切な — important, precious写真を — photo (object marker)間違えて — by mistake, accidentally消してしまった — ended up deleting, unfortunately deletedBecome a Makoto+ member for bonus content: www.MakotoPlus.com