]I'm not convinced that Anne's rejection of CW was an act of self-sacrifice to insure that he would go on to "fame and fortune," although as you wrote perhaps she saw it that way over time.

Same here, I have always interpreted it that instead of Anne deciding to give up the engagement as a way of helping him it was the other way around. She was pressured into giving it up and then decided it was the right thing to do for his sake as a way of consoling and coping with everything.

]I always assumed that he would not give up the sea even for marriage.

My thought is that if Anne had not broken the engagement, he would have been motivated to go right out to be successful, the sooner the better, so they could get on with their lives together.