It basically means that I will love you forever. 世界末日means the end of the world. It is used to refer to some time far in the future. However in the context, it says 不够远， which means not far enough. Here he is saying, even it's the end of the world, i will not stop loving you, that the day the world ends will not not be the end of my love for you. To make it easy, you can read it as "MY LOVE FOR YOU WILL OUTLAST THE WORLD." If you want to make it more simple, it just simply means "MY LOVE FOR YOU IS TIMELESS" Read the original sentence as "世界末日不够远,(put a comma here ）不是爱你的终点" might help you understand better. I know it's a little bit confusing, hope it helped you.

世界末日不够远： the end of the world is coming soon.---the ending time is not enough far from now. 不是爱你的终点：i will still love you----it's not the end of my love . it means even the world is damning,destroyed,im still love you..i love you forever.

you are right.“远”指的是时间，他的意思是，我会爱你很长很长的时间，比从现在到世界末日这段时间还要长