PPPD-402 Her older sister has big tits and is okay with in-the-vagina sex, and she's seducing me.

My girlfriend insists on using condoms and no internal ejaculation, and she has small breasts! Her older sister, however, has huge breasts and is incredibly sexy! For some reason, her older sister keeps seducing me and we do all sorts of dirty things! And when she says it's okay to ejaculate inside, my rationality flies out the window! I feel guilty towards my girlfriend and worry about getting caught, but I can't stop this feeling-good breast sex and internal ejaculation！！