[JLPT grammar] A decision made on one’s own or determination, ことにする? ことになる?

Today I am going to share the homework correction quoted from my JLPT course!
The student’s sentence is not correct. Can you find the mistake?

 

[Student’s sentence]

彼女にプロポーズすることになりました。

*かのじょにぷろぽーずすることになりました。

 



 

[My correction]

彼女にプロポーズすることになりました。
→彼女にプロポーズすることにしました
I decided to propose to my girlfriend

You should use ことにする because to propose was what you wanted.

ことにする indicates a decision made on one’s own or determination, ことになる indicates that something was decided by an organization or system.

e.g.
古(ふる)いパソコンがこわれたので、新(あたら)しいのを買(か)うことにしました
My old computer broke down and I decided to buy a new one.

疲(つか)れたので、タクシーで帰(かえ)ることにしました
I was tired and decided to take a taxi home.

今週(こんしゅう)から、残業(ざんぎょう)はしないことになりました
Our company will not be working overtime starting this week.

明日(あした)は7時(じ)までに学校(がっこう)に行(い)くことになりました
The school wants us to be at school by 7:00 a.m. tomorrow.

 

I hope my explanation helps you. 😊

 

In the JLPT course, all lessons come with homework, if you submit your homework, I will reply with corrections.
I can break down the Japanese grammar and point out mistakes, explaining the structure and nuances of Japanese in an easy-to-understand way.
You can also ask me any questions as much as you want. I will teach you until you get it!