Late at night, a person lies awake with a cup of coffee, surrounded by pillows and blankets, and thinks about someone who isn't there. That's the whole scene, and it works because it's so ordinary. The speaker isn't doing anything dramatic. They're just waiting out the hours, and the missing fills every one of them.
The details are small and comforting: warm coffee, soft pillows, a cozy blanket. Yet they only underline the loneliness. The speaker is hugging pillows because there's no one else to hold, and hiding under the blanket as if it could shut out the feeling. The line about hours "ticking by" slows everything down, so we feel how long these nights are.
The last line carries a quiet twist. Missing someone is called an "art" that the speaker has "mastered," which suggests that practice has made them skilled at it. The tone is tender and a little wry, tinged with sadness. The closing "~" softens it further, like a sigh trailing off.