I'm leaving yet I love you

• 1. this line sounds pretty bad, "moi ma"' instead of "moi la" is mostly used by kids, or in very casual spoken French. But since she uses an adjective - and a rahter posh one, besides - she has to put "ma" instead of "la". Very awkward
• 2. this line is all over the place. "tomber à l'eau' is idiomatic, to talk about a project that failed. Used with a person, it does not mean anything except actually falling into the water. "faire l'effort" is exactly like "do the effort [of doing something]", which does not mean much in this context. And to top it all, the sentence is unfinished (what effort?)
• 3. again that's really awkward. "croire fort" sounds childish while the rest of the sentence tries to sound elegant
• 4. that's most probably what she meant to say, but the French rather sounds like "you'd better split that smile pronto, boy!"
• 5. she switches to the deferent "vous" instead of "tu" out of the blue. That does not make any sense, unless she starts talking to a group of people or a different person