to enter; to come in; to join (a club, company, etc.); to enter (a university, the army, etc.); to be contained (in); to be included (in); to (be able to) fit (in a container, building, etc.)
Examples (3 in total)
わたしは慌てて二人の間に入る。
I hurriedly step in between the two of them.
第三者が間に入っても、ただ迷惑なだけだし。
Even if a third party stepped in, it would just be a nuisance.