The speaker is watching a person they care about stay with a partner who, in their eyes, is harmful. Everything circles around helplessness. The repeated "I wish" and the echoing lines ("See what I see / Know what I know") show someone trying again and again to be understood, and not getting through. They believe the partner will hurt the person, and that he is already pulling them away from others. "His actions are yelling" suggests he tries to hide his behavior but can't quite manage it.
The speaker's feelings are a mix of pain, frustration, and fear. They admit they can't see what the other person sees, which makes the poem feel honest rather than simply accusing. The final line, "Will I be next?", is the most worrying: the speaker fears losing the friendship or family bond altogether. The mood is anxious and heavy, like a plea no one is hearing.