What’s the name of this movie?

The film starts with a teenager (let’s call him M) who remembers a day at high when he saw his dream girl(let’s call her G) (both likes the same sandwichs)entering his school but she falls in love with a sporty guy, and after high school ends she broke up with him, he will meet her in a party with all of their friends from high school, M tries to impress G, while that sporty guy after he left G he is looking now for college women but his friends can not leave their Gfs, and there is another guy at the party who is M friend ( as I remember) he is trying desperately to find a gf and finally he finds a girl who just broke up with her bf and she is willing to date the first guy she meets just for revenge, he takes the chance and she will start dating with him , after that he goes to the bathroom ( we are still in the party ) and before he relize he finds out that he is stuck there becuase the door was broken from the insides and another girl enter the bathroom and before he warn her she closes the door and they will stay togather there and no one will be able to hear them because of the loud music , thats all I can remember if you think you know the movie plz write the name