News that Mary-Kate Olsen is engaged to marry Olivier Sarkozy isn’t exactly what you’d call run of the mill. When we first heard that this pair were a ‘thing’ two years ago a collective “eh?” was issued around the world, but we’ve all eaten our words since because here they are, still happily together and headed for the chapel.

mary kate olivier sarkozyMary-Kate is engaged to French banker, Olivier Sarkozy

At 44, Sarkozy is 17 years older than Olsen, and father to two children, aged 12 and 10. Had Mary-Kate not literally grown up on the screen, this pairing may not have been quite so unusual. We all have a habit of still thinking of the Olsen twins as the cute toddlers in Full House, so to hear that one of them is engaged to be married, and particularly to a man in his forties, is a little hard to digest, although it really shouldn’t be. In the grand scheme of couplings, 17 years is not really that big of an age gap.

Additionally plenty of young women marry much older (and very rich) men; however, not many of them already have as much money as Mary-Kate or were successful businesswomen by their mid-teens. In light of their engagement we look at other celebrity couples who could be classed as ‘unusual’.

Mariah Carey and Nick Cannon met in 2008 on the set of one of her videos. The pair have since married and are parents to twins Moroccan and Monroe. These guys have been together for six years now but we’re all still a little confused about the whole thing.  

Brody Jenner and Canadian pop star, sorry, legitimate punk rocker Avril Lavinge dated between 2010 and 2012. Brody is Bruce Jenner’s son and step-brother to the Kardashian Klan as well as ex-love interest of The Hills star Lauren Conrad. Avril Lavigne is now married to Chad Kroeger. We’re not sure whether we find her relationship with Brody or Chad more surprising. We can, however, be thankful that Avril and Chad’s romance did bring us their groundbreaking duo ‘Let Me Go’, because the music world would be a lesser place without it.

Mila Kunis and Macaulay Culkin were together for over eight years, and no one even heard about the relationship until about a month before they broke up. The Ukrainian actress is now engaged to That 70’s Show co-star Ashton Kutcher, but she doesn’t seem too ashamed to let the whole world know about this one.

mila ashtonMila has known Ashton since she began work on That 70's Show when she was just 14 years old

Woody Allen controversially left his partner of 12 years, Mia Farrow, for her adopted daughter Soon-Yi in 1992. Allen still can’t see what all the fuss is about: "I fell in love with this girl, married her", he said. For a multi-award winning screenwriter and director we thought Allen was supposedly skilled at tapping into the human psyche, so we're at a loss to understand why he's finding this one so tricky.

Michael Jackson and Lisa-Marie Presley. There are no words.

Who do you think is, or was, the strangest celebrity couple?