Not familiar with other sites, but I think someone has mentioned there might be one.
The type of cruise you want is unreachable in time, financially, and interest to most. Then there's added expense of airline tickets to get to a port or return home.
My dream is a sailing on one of the QUEENS, but that's where it will have to stay, a dream. To some, a transatlantic would be too long at sea, except for those who are already sure and already booked.
You may have to join a singles cruise. There are sites for solos. Just google and find the sites and decide. You can travel solo or apply for a room share.
Also may have to decide on another type of cruise.