You ask her if you can avoid wearing diapers somehow.

“Please Julie, sure there must be a way to be your boyfriend without wearing diapers, right?” You ask her taking together all your courage.

“How about a little bet, sweetie? The toilet is off limits for you, if you manage to keep your pants dry and clean for the next four hours, you can be my boyfriend without wearing diapers, but if you have an accident during that time, you will be a good potty pants and wear and use your diapers for good without complaining.” Julie suggests.

Feeling oddly confident about your victory, you agree to the bet.