through
off
over
out
Answer is Right!
Answer is Wrong!
The correct answer is: out.
The word “out” is used in this context to mean “to the end of a relationship”. For example, “They fell out with each other” means that they had a disagreement and stopped talking to each other.
The other options are not correct because they do not make sense in the context of the sentence. For example, “He has fallen through with his partner” would mean that he has failed to keep his promises to his partner. “He has fallen off with his partner” would mean that he has fallen off a cliff or something similar. “He has fallen over with his partner” would mean that he has tripped and fallen over while he was with his partner.
I hope this helps!