YOU SAID:

I have a crush on someone who has a crush on someone else

INTO JAPANESE

私は他の誰かに恋をしている誰かに恋をしている

BACK INTO ENGLISH

I'm in love with someone else I'm in love with someone else

INTO JAPANESE

私は他の誰かに恋をしています私は他の誰かに恋をしています

BACK INTO ENGLISH

I'm in love with someone else I'm in love with someone else