“O God, I have an ill-divining soul” – Juliet, A3, S5, L60
oh God, My mind predicts evil things
ill-divining. I think that this means she can predict really bad things that could happen. divining means to discover something through guessing, and ill-divining would mean that what you predict is bad.
I think this quote relates to the play like a lot of the ironic, foreboding lines do. before she says the line, she talks about how she will never see him again. she then exclaims that she has an ill-divining soul, hinting that when she guesses something bad, it ends up happening.