John Legend thinks Beyonce and Jay Z make marriage ''cool''.

The 'All Of Me' singer, who is friends with the couple, thought their performance of 'Drunk In Love' at the Grammy Awards last month was ''sexy'' and proved committed couples aren't boring.

He told BANG Showbiz: ''I loved it. I like seeing them display their love for the whole world to see.

''It makes me feel like I'm cool being married. We can be married and cool at the same time.

''Because they're so guarded, it was exciting to feel like we got a peek behind closed doors. It was really sexy.''

The 35-year-old singer, who married Sports Illustrated model Chrissy Teigen, 28, last year, is not afraid of public displays of affection and his wife starred in his music video for romantic ballad 'All Of Me'.

He said: ''We're not too shy when the moment's right, displaying our love for people.

''Particularly with that song it only made sense for her to be the woman in the video, because of how honest and real the song is. We felt we should shoot a video that reflected who we are as a couple.''

Meanwhile, both John and Beyonce recently performed at Michelle Obama's 50th birthday party and the 'Ordinary People' hitmaker was moved by President Barack Obama's speech to his wife.

He said: ''It was really heartfelt. It was really inspirational for someone like me who had just got married, to see a couple who have been married for quite a while now, they just seem so truly in love. Not like infatuation in love, but mature, seasoned, weathered love that's built to last.''