I’ve seen a Taiwanese series a long time ago and loved it. Trying to find a rom-com with the same trope  : rich play boy ML falling hard for the strong-minded, poor and ordinary FL. He’s devoted to proving his love for her is sincere but she’s not believing him because he’s been a play boy all his life. 

ummm i just recently watched an old jdrama Pride that is basically what you described! I don't usually watch jdrama but I was recommended Pride by so many ppl that I had to watch it and it ended up being really good!

I recommend The Great Seducer- ML is rich playboy who approaches FL because of revenge but then he falls in love with her, FL at first don't believe him because he was player all his life