Yes

You decide to stay. Afterall, she might come home eaely, or she could "make it up to you" in the morning, right?

After you kiss her goodbye, you go back to her room and lay in her bed. You're a little frustrated so you really wanna masturbate. You pull out your cock and begin thinking of your girlfriend. You think of her ass, and watching her slide those panties up onto her ass.

Then you remember what you saw earlier with her giggling. Curosity grows in your mind...