I don’t know what he’s doing now, but he’s not doing it with her.
The English translation for this sentence appears to have been changed to make it seem less vulgar.
The original translation on Tatoeba is “I don’t know what he’s doing now, but it’s not her” (i.e. the meaning being “he’s not having sex with her”).
Does this translation still work with the English having been changed to “but he’s not doing it with her”, or does es mit jemandem treiben always mean to have sex?