In Petrarch's Sonnet 333, the speaker's relationship to Laura is that she was his love, but now she has passed away. We see evidence that she was both dearly loved by the speaker and is now deceased in the very first stanza in which he says,"Go, grieving rimes[rhymes] of mine, to that hard stone / Whereunder lies my darling, lies my dear" (1-2). Since gravestones are ornamental stones set on top of graves, we know that the "stone" his "darling" is lying under is indeed a gravestone; therefore, we know that Laura is deceased. Not only that, the phrase "lies my darling, lies my dear" is very telling in that the terms "darling" and "dear" are well-known terms of endearment used to express affection for a "dearly loved" one (Random House Dictionary). Thus, through these two terms alone we can tell that Laura was a woman who meant a great deal to the speaker, one he loved romantically.
We can further see just how much Laura meant to the speaker when he says that he can no longer live without her, that his grief over her loss has made it impossible for him to continue doing in life what he needs to do, as we see in the lines, "Tell her, I'm sick of living; that I'm blown / By winds of grief from the course I ought to steer" (5-6). We even learn he feels his only purpose in life is to praise her and, therefore, without her he wants to die.