Here the speaker looks back on a parting and wishes it had gone differently. If only the other person had said "hold unto me," the speaker says, turning away would have been much harder. The line suggests a quiet regret: neither of them reached out, and the silence let them drift apart.
The third line is the emotional center. A memory the speaker believed was gone keeps coming back and "swallows" them every day, which makes the grief feel bigger than they can handle. Yet the ending is gentle rather than angry. Instead of begging the person to remain, the speaker offers a compromise: if you must leave, at least stay in my heart.
The mood is soft, wistful, and a little resigned. The short lines and plain, slightly imperfect wording make it feel like a private thought spoken aloud, honest and unpolished, as if the speaker is still working out how to let go.