I don't see the MC losing all concept of consent. Before I dated, I had this naive view about how there was always this kind of explicit agreement beforehand by the two partners that sex would happen. I remember quickly learning otherwise from my early experiences with dating and relationships. I could often, without thinking about it beforehand, and or even telling myself in advance I would act otherwise, be pushy about sex. But the girls would never have called what I was doing rape (sometimes they can be pushy about sex too, ya know). I was just horny, and sometimes they pushed back and I stopped---and sometimes they relented and decided they were horny too. In retrospect, I don't find anything unnatural or immoral about that. When the pushiness becomes violent, or involves drugging the other person, that's when we are solidly in bad territory; but the MC isn't doing any of that. Amelie could actually end it at any point if she really wanted to, but she doesn't really want to and that's why her resistance is often half-hearted. Anyone who's dated a woman understands that.
As I mentioned in my previous post, what's going on with Amelie and the MC is that they are losing self-control, having a harder and harder time being rational. Amelie, as the more mature person, is better at staying rational, but it's clear even she is giving in to the raw desire they feel for one another. It's also clear that the dev means for their growing boldness to be noticed, as we have a couple of specific moments that focus on Davie seeing them do things which draw his quiet attention. The fact that they're getting to be painfully obvious builds up suspense and concern on the part of the player, who will naturally wish for them to calm down before they get caught. The player is supposed to feel that way and to see what's coming, a building up to a dramatic moment in which the MC's secret relationship with the women is finally exposed. For sure we can expect an explosive drama in the coming updates. If we don't, and Davie's response ends up wimpy, then that's when we can say it's become bad storytelling.
Besides the plot development, another thing at play here is probably what the dev means for the player to feel here. I mentioned already the feeling of suspense and concern of the player to not get caught. But there's another layer here, which is that the story has been a slow burn, building up more and more the desire of the player to finally see Amelie and the MC fuck. The increasingly strong desire of the player to see it happen is mirrored in the characters themselves, in their feelings and actions as increasingly lacking control. This mirroring is purposeful. Precisely why the player feels concern is because the player also feels growing and irrational desire as the characters do. The potential of that desire being foiled and remaining unsatisfied helps build up the feeling of suspense in the player. If you're feeling that suspense in abundance, then the dev's storytelling here is clearly successful. You should be feeling that you really don't want them to fuck things up before they fuck, while at the same time sharing the MC's desire to finally fuck Amelie now, now, now.
Anyway, I will say the one time I thought it was a bit over the top was when they were in the ocean and their family members were hitting the ball back and forth. Maybe that one was just a little too obvious and in the face of Davie. I suppose the dev just wanted us to feel that way intensely and was willing to push the envelope of believability to achieve it. I remain ambivalent on that one. My thought there is that it wasn't the worst idea, but perhaps the execution of that event could have been better and more believable somehow.