Well, the classic joke is that the girl with large breasts complains about how much of a pain they are (e.g. stiff/sore shoulders), and the girls with small breasts want to kill her.
That being said, while I love big boobs, there's got to be a limit past which having them be any bigger just makes life harder on the girl without really benefiting the guy (or helping the girl get a guy). And on that basis, her breasts are probably a bit too large, but her boyfriend sure enjoys them, and complaining about them helped her officially nab him. :)
And in reality, most girls don't get breasts anywhere near that large without enhancement. But with hentai, reality doesn't matter so much...
I tend to agree, but I find it to be a huge turn on when a guy wins a girl over by making her feel good (particularly when the focus really is on making her feel good and winning her over and not just him slamming her with his cock better than her boyfriend/husband does - or even worse, simply having a bigger cock). I prefer that the boyfriend not be be in the story precisely because I'm not big on cheating/NTR, but him winning her over like this is incredibly hot and (at least for me) softens the blow that she seems to have been in a good relationship prior to this.
Now, I suppose the question is whether the guy will win her over completely (which he probably will given how these things tend to go), but sequels are rare enough that I bet that we never see where this goes...
Yeah, though he _did_ give out on her after cumming, which is her complaint, so either it's kind of weird that he can then do 62+ push-ups (with her on his back no less), or he needs to build up different muscles than what he uses with push-ups. But it was done for comedic effect, and reality and hentai often don't get along...