I've been watching Hong Kong TV serials recently. 2 incidents in 2 different series have set me thinking. A male character were diagnosed with a terminal disease and do not have much time to live. Both of them have a steady girlfriend. Not wanting to burden their girlfriends, they acted mean to their girlfriends and tried to break up with them. Is this a noble act?

I disagree. They are just trying to be a hero. If their girlfriends are truly in love with them, by denying them the opportunity to share their weal and woe, it's doing a disservice to them. It's belittling them. If they are not willing to take the burden, then it should be their choice.