Here is a summary of the poem:
The poem uses the metaphor of lipstick to represent obsession. The speaker seems to be infatuated and obsessed with another person, but they are incapable of real, and true love. Instead, their desire manifests itself in a twisted, almost lustful way.
In ‘I love it’, ‘It’s Smooth’ and ‘Stunning’, the speaker first describes their lover's lips painted with red lipstick in vivid terms, comparing it to lava. Even angels, those above the earth would cry if they saw such a beautiful colour. And the devil, who is in hell, seen all of the earth’s core, has never worn the colour. This shows how the speaker holds the lover’s lips in high regard, and shows the beginning of this obsession. Besides seeing the red-painted lips, they hope that the lover’s organs burn, so that they can see the redness inside..
The speaker and their lover are intimate, and their passion is heated. However, the speaker’s obsession goes deeper - they start to imagine the lover's insides as also being red, and find the colour beautiful.
In ‘Unmatched’, the speaker see the Lover wearing the lipstick. They see their lover as innocent, but the lipstick they had put on is so ‘sinister’. This is due to the obsession starting with the lover’s red painted lips. The speaker admits that they are starting to get obsessive.
In ‘Addicting’, the speaker imagines the lover’s heart, with blood gushing out. They hope that when they are able to see the colour of their lover’s heart, it would be able to be a perfect match in fueling their twisted desires. The speaker is starting to get unhinged.