Mick Jagger and Longtime Partner Melanie Hamrick Got Engaged Years Ago

Mick Jagger's found his rainbow, and he's looking to lock her down for the rest of his life ... because he and his longtime partner Melanie Hamrick are engaged -- and have been for some time.

Hamrick let the news slip during an interview with Paris Match, published Wednesday ... revealing the Rolling Stones lead singer actually asked her to marry him "two or three years" ago.

For anyone thinking Keith Richards and Ronnie Wood should start practicing Felix Mendelssohn's "Wedding March," don't be fooled ... Mick and Melanie aren't rushing into marriage -- 'cause Hamrick says she's too afraid to change their current routine.

Jagger and Hamrick met way back in 2014 ... while Mick was touring in Japan with the Rolling Stones and Melanie was performing with the American Ballet Theatre. Hamrick met Jagger backstage at one of his shows -- and, later traveled to Zurich to meet up with the band.

The two sparked a romantic relationship shortly after ... and welcomed a son -- Jagger's eighth -- in 2016.

While many have criticized the 44-year age gap between Jagger and Hamrick -- he's 81, she's 37 -- Melanie told Paris Match she doesn't worry about outside opinions ... after all, she's happy.

As for Jagger, he was married to Bianca Pérez-Mora Macias from 1971-1978 ... and he and Jerry Hall were unofficially married from 1990-1999. This would be Hamrick's first wedding.