[Dann of Thursday]

-As far as I saw, Shirley never demonstrated openly to him that she disliked him gambling. We saw her make comments, but none to him that I recall.
-He didn't want to really remove her memories, but given the state she was in it was for her own good.
-But he did it anyway.
-She was going off to see Mao who is pretty much a psycho. I wouldn't have let her go either. Besides, what does that incident have to do with happiness?
-But he didn't appear to have any attempt to harm her. She would have probably been forced to leave and thus wouldn't have been an issue to worry about anymore.
I'd go on, but I don't really feel like it. Any of those points are arguable to some degree. Pretty much every act in some way contributed to the goal of either helping the plan for a peaceful world for Nunnally or keeping those he cared about out of danger.

Besides, who said that he was always an altruistic person since most of us admitted he wasn't completely like that at all. Euphemia is probably the only example of a completely altruistic person in this show.

All we're saying is that when it comes down to it in the end, Lelouch's happiness is second to those he cares about.

Of course pairing preferences go into ideas of when everything is over. He won't be going back to school though since everyone would have graduated by then. It would also be sort of a lame ending to win against a world empire and go back to being a simple student with an everyday life, which it seems bored Lelouch quite often with some fun times here and there.