The speaker describes themselves as cold and guarded, someone with their "back against the wall" and a "forcefield up." Touch is something they keep at a distance. The person they're addressing is the opposite: intense, hot, with "lava in your gaze." The title, "Melting Point," pulls these two images together. It hints that the speaker's defenses are exactly what this other person can wear down.
The poem sets up a question, "which is stronger, fire or ice?", and then answers it in a surprisingly quiet way. There's no dramatic clash. The answer comes in the last line, as "our fingers intertwine." The speaker doesn't say who wins, which suggests the contest was never really the point. What matters is that the speaker lets someone close. The mood moves from wary and self-protective to tender and a little amazed, as if the speaker is realizing, mid-gesture, that being touched isn't something to fear.