
The explanation is Animal Instinct. Not everyone can control their true nature we are all animals after all even though we pretend we arent. No male mammal ask for permission from the female mammal to have sex. Whats stops humans from doing the same is the law and morality but the problem is that the law is not always watching and not everyone is moral. Sad but true. About yaois blame all the fujoshis out there who are into forcefull stuff for this, there are actually a lot otherwise there wouldnt be so many yaois portraying rape, they draw what sells best, always. Honestly I dont even care about rape in yaoi at this point, I dont like it nor dislike it, its standard so I just accept it and focus on the plot or anything else the manga is offering

http://www.mangago.zone/read-manga/shiba_kun_to_shepherd_san/ this one, the poor seme keeps trying to have some fun but uke-kun keeps saying no, Im not ready, It will hurt and so seme-san respects him everytime and stops. The Seme doesnt get angry with him and treasures him the same. The one who gets angry is me tbh, uke-kun is a bit annoying IMO but I think you might like this one, at least like you said For once youll get to see what you want.
Why is it that every time an uke says "NO" or "Please Wait" or "Stop" the Seme never listens!!! I mean here is the poor uke scared, confused, not knowing what's going on and the seme always doesn't listen and just does whatever he wants to the uke!!! Plus on top of that the seme thinks that just because he says that he "Likes Him" it's going to be ok? Really! ( ̄へ ̄)No that's not right!