Yes, they drowned themselves in the last chapter but then were reincarnated. Because of the reincarnation they were able to meet again in a future life
ml was framed (i think) and the police think he was the killer to several people so if he got caught most probably he gonna get death sentence and the mc happen to accidentally killed the creppy uncle that about to rape him + he help the ml (who is a suspect) to flee away which make the police consider him accomplice so they just decide to do couple suicide so they can finally be "free" loving each other without needing to hide from police
Did they off themselves at the end? I was a little confused at what exactly happened.