I'm not that surprised. I'd heard whispers about this when he was still a Congressman. IIRC, he didn't get married until relatively late in life.
Hopefully, the encounters (if true and that is a big if) are in the distant past and he has put that lifestyle behind him. He is a good senator. He has a good voting record even if these accusations are true.
When Studds and Crane got caught with the interns in 1983, Rep Craig at the time held a press conference denying he had an intern problem. But nobody accused him in the press of it anyways. That is why folks got suspicious back then.