If you had the opportunity to know everything about the person you love, would you take it? Or would you avoid the possibility of getting hurt?
Dear lord, no. There are things I don't like knowing about MYSELF, even some things that other people already know. I must presume that anyone else has things they Really Rather Would Not have anyone else know, and for good reason.
(One reason I feel EXTREMELY strongly that privacy is a necessary component of any human civilization, and that this is important enough to mean that yes, at some point you must draw the line and say "Yes, privacy, even if it means that some people will suffer for it.")