Yes sure. But that did not stop him from beginning a romance with Marianne Lenoir at the age of about 108. And she did not have to be his first romance. He lived a long time ...
By the way - it was around 1940, when the two were separated. If Marianne was 20 years old at the time, she would celebrate her 99th birthday in 2019. But she does not look that old, despite the walking stick. Could it be that the amulet she got from Master Fu extended her life?
I don't know about Master Fu being Marionette's ancestor. That seems a little farfetched for me---what are the chances that the person he chooses to be Ladybug/the next Guardian is actually one of his own descendants? But I guess it's always possible. And hey, I'm toying with the idea that Marianne is one of Adrien's ancestors, so who am I to judge?
I'm actually really interested in Master Fu's past. I want to see how he got to Paris, and how he became a part of the Resistance against the Nazis. Did he use the Turtle Miraculous to fight against them? Did he give Marianne a Miraculous? It'd be really cool if there was a 1940s version of the Quantic Kids. And what about his other relationships? It'd be great to explore how the Last Guardian navigated life during one of the most turbulent times in France's modern history. I almost wish Thomas would create a spin-off just for that.
I do not believe the amulet is a miraculous. After all, no kwami appeared when Wang Fu handed over the amulet.
But I'm convinced that it holds an important secret. Maybe it has a magic that prevents disease. Marianne looks - apart from the walking stick - remarkably fit and healthy. And that at the age of over 95 years.