Japanese by Example
Learning through examples in manga

To end up cleaning for you with 〜ことになる

Grammar Explanation: To end up being with 〜ことになる

それでも歩は寄せてくる » Volume 2 » Page 134

Urushi and Ayumu give their makeshift clubroom a cleaning to welcome potential new members. Considering that Urushi was the only club member before he joined, Ayumu remarks how she alone had cleaned the room for his sake last year.

うるし:
「まぁ　結局(けっきょく)」
"Well, in the end..."
「お前(まえ)しか入部(にゅうぶ)してないからそういうことになるか」
"You were the only new member, so it ended up as you say, huh?"

The focus here is on Urushi having cleaned only for Ayumu as the result of him being the only one who joined the club.