Most cruise lines have GLBT social get togethers. Usually in one of the bars. You will find the listed as "Friends of Dorothy". (A VERY old term from the fifties.) Sometimes these meetings are not listed in the daily scheduel that you get in your cabin, but rather at the "Special Group" activities board near costumer service. We have met some cool people at thease meetings.
Also NCL has a ship or two with single "studio" cabins. Thease appeal to lots of single travelers including gays. These ships have an area where singles get together daily. Jimbo