http://www.mangago.zone/read-manga/sweetheart_v5_the_boss_is_too_kind/nto/to_chapter-83/12/ If you read from that page to chapter 84 they kissed but with a more erotic "mood" than before (even our pure Yiren could realized), he stops after she asks him if they are "making love" to what he feels the need to explain that they are "just kissing" (as if doing more was out of the picture, which was not) and then he tries to convince her of having sex by telling her that doing it it's their duty as a married couple. The buttler butts in and the "mood" is cut off but he was being pushy about it, knowing she's not fully aware of what she's doing and after trying to brainwash her into it. So just because he didn't do it doesn't changes the fact that he lied to her in order for them to have sex.
This was the first http://www.mangago.zone/read-manga/sweetheart_v5_the_boss_is_too_kind/nto/to_chapter-84/3/
It might seem like nothing without the context but that explation was after this http://www.mangago.zone/read-manga/sweetheart_v5_the_boss_is_too_kind/nto/to_chapter-84/
In that scene the "uncle" was aming to do more than just a kiss, so all that a explation abut the kiss being a greeting was a lie.
Then this happens http://www.mangago.zone/read-manga/sweetheart_v5_the_boss_is_too_kind/nto/to_chapter-84/7/
And on the next page to that one he tells her that "making love" is "the gratest DUTY that a husband and a wife could have to eachother". So instead of explaining her what actually happens during intercurse he makes it seem like it's basically mandatory(the fact that he "asked her" if she wanted to do it doesn't changes the way he phrased it as something that's due to obligation). "nothing" happening doesn't make any of that better.
This guy is an idiot! Since chapter 1 it's been stated that she has some kind of mental handicap (we know she doesn't but they believe she does) and even tho she has proved to be quite smart it's obvious there's something going on. He was aware of her supposed mental handicap so he shouldn't have lied to her in order to do naughty things, that's considered to be rape. She's right so why is he so offended by her statement
ヽ(`Д´)ノ