Krik? Krak? "Children of The Sea"

I am not an avid reader, and it takes something very interesting (to me at least) in a book or any reading to keep my attention. "Children of The Sea" was a very interesting story in its context because it was two people who were in love writing letters to one another in which either persons would never see because the man was in a boat fleeing Haiti. The letters contained all kinds of expressions towards one another including passed conflicts they had "I look up there and i think of you and all those times you resisted. Sometimes i felt like you wanted to but I knew you wanted me to respect you" this is a prime example in  which I think they may be referring to sex The father opposes there love and gave up all of his possessions to protect his daughter. What intrigued me about this tail is the ending because it leave you wondering if they will ever see each other. One question that i asked myself in reading this is what the black butterfly symbolize? Black always symbolizes death and butterflies usually symbolize freedom. So how do the two conjoin? I wonder if he made his escape, or if the boat was him that sank.