Gigi Hadid and Zayn Malik 'Squish' in PDA-Filled Pic

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Absence clearly makes the heart grow fonder.

These two are definitely back on.

After celebrating Fourth of July with a girls' weekend at Taylor Swift's annual Rhode Island soiree, Gigi Hadid is back in the arms of Zayn Malik.

WATCH: Taylor Swift and Gigi Hadid Were Totally Twinning in Red, White & Blue Swimsuits During 4th of July Bash

In a snap posted to her Instagram, the 21-year-old supermodel comes face-to-face with her on-again beau -- literally -- as he leans in for a kiss.

"Squish ya," Hadid captioned the pic.

Although PDA is nothing new for the couple, it's the first we've seen since they reconciled last month. 

Though Hadid and Malik are clearly back on, a source told ET when they rekindled their relationship last month -- after a week-long break up -- things are still a bit rocky.

"Yes, they're back together, but [it] could be over again in any second," the source said. "Gigi is obsessed with Zayn -- she won't let go of him too easily."

Judging by their Instagram accounts, it's easy to assume they're pretty obsessed with each other.

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The couple doesn’t just show off their PDA on social media; they've also taken their love to the pages of Vogue.

See more in the video below.