you where Bills bestfriend and you where kinda close to tom. but you where having a sleepover at their house and bill went downstairs to help his mom with something. at that time you and tom where in bills room alone..

tom: ive wanted to ask you for a while but.. will you be my girlfriend?

you said yes and now yous are kissing. bill walked in (bill was going to ask you out cause he's had feelings for you for months)