The melody of The Lonely by Christina Perri runs 251 notes across 52 bars, 3:22 long in Cm at 75 beats per minute. The tab sits low on the neck, mostly under the fourth fret, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? The Lonely chords and lyrics.