OK some hints for those of you that want it:
1) Every time you get an "A" ending, if you wait until the end credits, you'll see a scene of Serafina dreaming--her thought bubble always contains a correct answer, so adjust your next game accordingly.
2) The B and C endings differ based upon a choice you never would have expected:
3) There is a
fourth ending, called "BC", where you grab Serafina's tits with BOTH hands. Otherwise it seems to be the same as B or C. I'm not exactly sure how I got that one: I took her to the sea after dinner and chose the "See...panties" option. I also had just won the poker game against Serafina, but I'm not sure that mattered, but thought I'd mention it,
For every ending you get, you get another credit towards the SuperPoker game. Which is VERY difficult to get without all extra credits.