The two are also said to be in a relationship, but neither has publicly commented on their personal ties.
Ms Rayner is silent on Mr Tarry’s resignation and has chosen to focus on the government’s track record.
In a tweet after the news came out, she criticized transport secretary Grant Shapps, claiming the outgoing minister had “spent more time on his doomed leadership bid than solving the strikes”.
She added that it was a “serious dereliction of duty” and that Labor “would always defend the right of working people to organize and withdraw from their work”.