Told as a string of questions, the poem sounds like a speaker pushing at someone they depend on. Each pair of lines asks how strong, how high, how far, how much, how long the other person can endure, and each time the answer is undercut by something cruel or careless. The speaker is "holding" a hand, then pulling the person "to your knees," then cracking and breaking them. The tenderness of the opening, with its image of someone "ever protecting, guarding me," slowly turns into a picture of damage.
The final question, "How long will you stay," is where the speaker's real feeling comes through. It sounds less like a threat and more like fear: the speaker is "always so far away," and seems to suspect that the loved one will eventually leave. The mood is uneasy and sad, a mix of guilt, need and self-sabotage. The title's farewell phrase hints that goodbye is already in the air.