So yes if Aryan is impotent then Vaidehi can't have a proper physical relationship with Aryan.
And for a married woman , its every womans marital right to share physical intimacy.
Do you think a guy would have tolerated it if his wife had aversion to physical intimacy and he couldn't get that satisfaction ? No way !! He would have asked for a divorce and these issues are serious.
This is what i think the "agni pariksha" could mean.