Prompt: End an argument with "Because I said so." Bonus if it's Lily.
The Three Broomsticks was bursting with life as Remus, Sirius, James, Peter, and Lily sat at a table discussing what Lily and James were going to do for their wedding. Lily's idea was a very elegant, muggle wedding that she wanted to invite her family to, while James and Sirius kept coming up with magical ways to have a wedding. Remus kept agreeing with Lily while Peter stayed silent, listening to the arguments, and drinking his butterbeer.
"There is this gown by Priscilla of Boston that I keep looking at. I can try it on in London and I think it's the one I want," Lily explained to Remus. "Do you want to join me when I go?"
"Of course I want to go. As long as your mother and sister don't care, that is."
"My mom doesn't care and my sister won't be joining me, sadly. She agreed to come to the wedding only because my mom convinced her to."
"I'm sorry about that."
"It's not a problem, Remus," Lily started.
"What if we do a wedding on broomsticks?" James said getting very loud and excited.
"James Potter," Lily said sternly as she stood up. "We will not be getting married on broomsticks or including any magic in our wedding. The only thing I agreed to is magical photos."
"Awww…. Why not Lily?"
"Because I said so," she said firmly.
"You lost this fight, James," Peter said finally speaking up.