John Legend & Chrissy Teigen -- So Cute You'll Wanna Puke (PHOTO)

John Legend and Chrissy Teigen just took being "that couple" to a whole new level.

The two -- technically three -- were at LAX Friday and started off 2016 in color-coordinated outfits.

We're not saying we're jealous or anything, but if "relationship goals" existed ... this is it.