In just a few lines, the speaker admits to a painful kind of love: watching the person they care about be happier with someone else. The poem treats this as a kind of burning, a slow, private hurt that comes from seeing it up close. Yet the speaker doesn't ask for the other person to come back or to feel guilty. Instead, the final line turns on the word "but": "i want you happy, so i'll bum."
That last word is most likely a typo for "burn," and reading it that way, the speaker accepts the pain as the price of the other person's joy. The repetition of "burn" makes the choice feel deliberate, almost like a vow. The dash before the turn works like a breath the speaker takes before giving in.
The mood is sad but tender. There's no anger here, only resignation and a love that puts the other person's happiness first, even when it costs the speaker something. It's a short poem, and its brevity makes the ache feel quiet and restrained.