Some celebrities seem destined to have ended up together, such as Beyonce and Jay-Z or Blake Lively and Ryan Reynolds.
But other short-lived relationships can be absolutely shocking.
For example, before his string of high-profile marriages, Tom Cruise was linked to one of the biggest musical sensations in the world - Cher. Brad Pitt also dated his co-star Juliette Lewis, despite a 10-year age gap.
Many fans will have forgotten the long-term relationship between Sarah Jessica Parker and Robert Downey Jr, or that the brief romance between Madonna and Tupac ever existed.
Here, we take a look at some of the most unusual Hollywood romances which sadly weren't meant to last.
Tom Cruise and Cher
Tom Cruise once enjoyed a fling with Cher after they first met in 1985 when he was 23 and she was 38.
The Strong Enough hitmaker had already been married and divorced twice by the time she met Tom at Madonna and Sean Penn's wedding in Malibu.
The pair were then reunited at the White House before embarking on a passionate relationship.
Cher later gushed about their "deep connection" and hailed Tom as one of her "greatest lovers ever".
Appearing on Watch What Happens Live with Andy Cohen, she revealed: "I had just the greatest lovers ever. Not a long list. It's just a good list."
When the TV host grilled Cher about her relationship with Tom, she admitted: "He wasn't a Scientologist then. It was pretty hot and heavy for a little minute. He's a great guy. The person that I knew was a great and lovable guy."
She added: "He was in the top five."
Madonna and Tupac
Madonna and Tupac Shakur enjoyed a secret whirlwind romance that the Material Girl hitmaker revealed to the world during a 2015 interview with David Letterman.
"I was dating Tupac Shakur at the time, and the thing is he got me all riled up on life in general," she said. "So, when I went on the show, I was feeling very gangsta."
An emotional letter Tupac had written to Madonna during his time in prison shed more light on the depth of their love.
The three-page love letter which was obtained by TMZ mentions a fight the couple had and the pressures Tupac felt while dating her.
"An interview where you said 'I’m off to rehabilitate all the rappers & basketball players' or something to that effect those words cut me deep seeing how I had never known you to be with any rappers besides myself. It was at this moment out of hurt & and natural instinct to strike back and defend my heart & ego that I said a lot of things."
He went on to admit that he felt "intimidated" by Madonna's sexually liberated persona and her "sex symbol" status which she had earned in the late 90s.
Tupac ended the note asking Madonna to come and visit him, as he would have "loved to speak face to face" with her.
Winona Ryder and Matt Damon
Following her failed engagement with Johnny Depp, Winona Ryder was introduced to Matt Damon by actress Gwyneth Paltrow.
Their relationship lasted from 1998 until 2000. Despite their split, Matt still gushed about his ex-girlfriend in a 2004 interview with Playboy magazine in which he called her a "great woman".
Winona also had nothing but praise for Matt, telling Black Book in 2009: "Matt couldn't be a greater, nicer guy. I'm really lucky that I'm on good terms with him."
Sarah Jessica Parker and Rob Downey Jr
Robert Downey Jr started dating Sarah Jessica Parker after they met on the set of Firstborn. They dated for seven years before splitting in 1991, with the Iron Man actor later admitting that drugs and alcohol were to blame for the split.
"I liked to drink, and I had a drug problem, and that didn't jibe with Sarah Jessica," he admitted in a 2008 interview with Parade.
He added: "It is the furthest thing from what she is. She tried to help me. She was so miffed when I didn't get my act together."
Brad Pitt and Juliette Lewis
Brad Pitt met his ex-girlfriend Juliette Lewis on the set of their 1990 film Too Young to Die.
Despite Juliette being just 17 at the time while Brad was 27, the pair hit it off and went on to become one of the hottest couples in Hollywood. The former lovers dated for three years, but decided to call it quits in early 1993.
While Juliette later said Brad is "not in my universe at all now", Brad gushed over his ex-girlfriend as he reminisced on the "great time" they had together.
"I still love the woman. There's some real genius there. I had a great time with her," he admitted in an interview.
"It was one of the greatest relationships I've ever been in. The problem is, we grow up with this vision that love conquers all, and that's just not so, is it?" he told Vanity Fair.
Jared Leto and Cameron Diaz
Despite the pair being Hollywood actors, Cameron Diaz and Jared Leto managed to keep their romance a secret after first getting together in 1999.
In fact, the Telegraph once called them one of "Hollywood's most photogenic, but least photographed couples" because the pair seemed to avoid being seen together in public. They also remained tight-lipped when asked about their romance in interviews.
The couple weren't meant to last, however, and they split in 2003. Neither one has commented on their romance since the split.
