There are a couple of things that can possibly improve the sex scenes. After the girls reach orgasm, have them show some exhaustion. For example, have them lower their body form/pose as if they have a harder time staying up. Currently, they stay at the same pose which makes it feel the ladies have more infinite stamina than the guy. Make the ladies look they are breathing harder after orgasm by adding a slight amount of wobble and panting as if gasping for air. Make their gaze look unfocused and dreamier after orgasm. After all, they just experienced orgasm and they should still be mentally fuzzy (instead of them giving intense gaze to the main character as if nothing happened).
I also agree with
Abduxuel about the amount of girls. I guess it makes sense for an orgy to take place on the final scene. But there were so many girls that it felt like a shore kind of like wanting to make sure he did fornicate every girl during the orgy (which technically he didn't but every girl did orgasm one way or another). To be honest, more than 3 people orgy (2 women and 1 man) starts feeling like someone is getting left out for a short time. I would rather prefer each girl have a separate sex scene at the end like as the protagonists visits each of them; one at the time. But it does mean more story and work; but this way the attention given to each person is more complete.
P.S.> I wonder if NTL media would ever consider making sex simulation games instead of RPG story driven ones. By sex simulation i mean like being able to control the various sex positions, camera angles, fornication speeds, actions, etc. I would really love such game; specially with the graphics for heir models. They really make the best looking ones I have ever seen so far. Even heaps and bounds better looking than the Japanese Illusion game models. Although i guess this is the advantage of pre-rendered scenes instead of a real-time 3D rendering game.