I've been looking for the name of a sci-fi romance book about space travel but haven't been successful so far. I came across it a few years ago, read the plot on its back cover but didn't read the book. It is about two spacecraft pilots, a man and a woman, who travelled at light speed (or maybe FTL, I can't remember) in separate ships. Every time they return to Earth, centuries have passed on Earth because of time dilation. They meet each other for a few times on Earth in different eras, but don't know when, if ever, they will meet again. I don't know how it ends.
If anyone knows which book I'm talking about, could you please tell me the name? Thanks a lot!