And that's the case in this game. Characters say "no", define their boundaries, and the sketchy MC keeps pushing with no input from ourselves.
If you start qualifying it (like the "no" has to be "emphatic" or it does count?) that's a troubling slope to start slipping down. It's honestly put me off this game quite a bit and the eventual sex scene with the eldest daughter when she doesn't say no did nothing for me.
The counter-argument to that would be that the characters in question kept an opening (mixed signals) for the initiator to try again with a different approach and that muddied the line between emphatic NO with "no?". The things that the male character does with the MILF and what the younger daughter does with the male character showcase the perfect example of the aforementioned scenarios. Here, the initiators are hell-bent to get what they want while the receiver initially denies their advances, leaving a door open for the initiator to try a different approach.
Here, both our male character and the second daughter are what we call classic manipulators. Sure, what they do is rape
but their intentions (so far) are not laced with malice. Once malice comes into play(when the receiver believes the initiator has malicious intent), all those pushing the boundaries, nagging etc. will be seen in a different light by the receiver, which makes things clear. Having said that, actions have consequences, and negative things done with good intent will have punishments, intended or not.
Another train of thought is the level of tolerance one has to something, like for example, your tolerance line is crossed when someone pursues even after saying no, regardless of the signal it is given in, some tend to have a higher tolerance to tolerate certain action before calling it enough.
This is why I wrote humans are strange. How I defined rape was when it was in a black-and-white scenario, that even the thickest of the skulls (read initiators) can understand but things get complex when mixed signals come into play.
A gentleman/woman will definitely give up after a "no" but then again, there is also a saying that "all's fair in love and war".