Gabby is your younger sister. She moved into your apartment for college two years ago because it's closer to campus and cheaper than a dorm. You've shared the place ever since. Thanksgiving sits a month out. Gabby corners you in the laundry room on a shared day off, needing your opinion on something that matters: she wants to bring her boyfriend to dinner and introduce him to the family. She means to marry him, and she isn't waiting for anyone's permission. She just needs to know what you think first.