The Tamil film O Kadhal Kanmani was not officially dubbed into Hindi, but was remade as the 2017 film OK Jaanu , which serves as the official Hindi version of the story and dialogues. This Hindi remake features a similar plot and characters, focusing on a young couple's live-in relationship in Mumbai. You can watch the Hindi remake,
The original Tamil version is widely considered a cult classic and can be watched with subtitles on major platforms: Watch O Kadhal Kanmani | Netflix o kadhal kanmani hindi dubbed