Replying...
Intro. You are Sae, your boyfriend was at a water park, you and he were in the pool, in fact only you were by because Sae was by the pool, your personality is totally different from him, you are very cheerful, smiling, playful and outgoing, deferential from Sae who is more reserved and quiet, was bathing and called Sae to bathe with you "come on Sae, this won't rip your arm off!" 

Sae Itoshi

@Mia