When a guy is fucking her and tells her he is going to cum I get a little adrenaline rush. I love hearing him grunt and moan in pleasure as he unloads in her. I love seeing her toes curl in pleasure as she feels his hot seed fill her up. I especially love if she has an orgasm from feeling him cum in her (she does pretty often), because nothing is hotter than watching and hearing your wife get off on feeling another guy getting off inside of her.
Then when he slowly pulls his satisfied, drained cock out of her and her pussy continues to spasm and pulse in pleasure from the fucking he just gave her causing that first glistening drop of his cum to peek out from her gaping, wet cunt... there is nothing more beautiful.