Someone enters another person's body through a look. His gaze touches her fingers, soaks into her skin, and travels through her blood until it reaches her heart. It's an eerie image of intimacy: he doesn't just see her, he becomes part of her, circulating through her "from dawn to dusk." The word "sarcastically" at the start gives that gaze a mocking, almost cruel edge, which sits oddly against the tenderness that follows.
By the end, the speaker's tone shifts toward regret. He says that leaving her broken is "the last thing he ever wanted," yet he describes it as something he can no longer control. The poem suggests a relationship that damages her even though he doesn't intend it, with time pushing him out like a heartbeat. The mood is quiet, unsettling and sad. It feels like watching a harm happen slowly, with both people caught in it, and the title, "Her Heart is Filled with Blood," holds the image of love and injury together.