YOU SAID:

my Boyfriend farts way too much and sometimes the smell is really bad and I have to open all the windows

INTO JAPANESE

彼氏のオナラが多すぎて、時々臭いがひどくて窓を全部開けないといけない

BACK INTO ENGLISH

My boyfriend's farts are too stinky sometimes and I have to open all windows

INTO JAPANESE

彼氏のおならは時々臭くて、すべての窓を開けなければならない

BACK INTO ENGLISH

My boyfriend's fart sometimes smells and has to open all windows

INTO JAPANESE

彼氏のおならは時々臭いがして、すべての窓を開けなければならない

BACK INTO ENGLISH

My boyfriend's fart sometimes smells and has to open all windows