i get what you mean to a certain extent. i sometimes feel excluded from sex too, sometimes for years on end, though most recently most of that was due to my own desire to be excluded from certain types of social interractions and situations and keeping to myself and not putting myself out there in enough quantity to get that.

that said though, if you are asking for it genuinely and in a socially appropriate manner (when you got reasonable expectations they want it too, after some amount of conversations where they basically let you know they want you etc) eventually you'll find someone who wants to do it with you. i feel like its a numbers game and also can be highly stressful process but yeah i guess mostly id encourage you to never give up regardless.