Does this count? They blackmailed each other into a stalemate and became buddies. They didn't even use the blackmail for sex reasons. Seme did it so his boss (uke) would stop eating his noodles and making him work overtime. Uke did it to cancel out the seme's blackmail.
http://www.mangago.zone/read-manga/ore_to_joushi_no_kakushikoto/
I guess this counts as the uke not really caring about being blackmailed? He's so 'meh' about the whole thing while the seme's the one getting flustered.
http://www.mangago.zone/read-manga/fujunai_process/
I think I read one about someone not letting themselves get blackmailed but it was only one chapter and I never bookmarked it. :(
To read a plot where the main character doesn’t let themself get blackmailed or doesn’t care that they are being blackmailed. I’m so tired of the same old dudes being scared into sex like wtf