Abbie's poem takes a very familiar piece of advice, "love others as you love yourself," and quietly turns it over. We usually hear that rule as a lesson about how to treat other people. Here the focus shifts to the second half: the part we tend to take for granted. The poem points out that the rule only works if you already know how to love yourself, and it suggests that "you" may be wrong about that.
The speaker doesn't sound angry. The tone is calm and a little teasing, almost like a friend raising an uncomfortable question. The word "believing" does most of the work, because it hints that this confidence might be an assumption rather than a fact.
The mood is thoughtful and slightly unsettling. If we don't truly know how to love ourselves, then the way we love others could be shaped by that same gap. The poem leaves the reader to sit with that doubt.