No sequel ? Wedding and so forth ?

The "wedding" was probably the party they had at the end. Since Saku and Ryota can't legally marry, Saku's parents adopted Ryota instead so he can be part of their family. Friends and family know that means they're in a relationship, but for publicity's sake, Ryota is the adopted son of the family. At the end, the party was to celebrate Ryota getting adopted, so that's as close to a wedding as you can get I guess lol An unofficial one would have been nice though.