5 celebrity breakup stories from 2015

After about 18 months of being engaged, Sean Penn and Charlize Theron have reportedly split.

The Mad Max actress was first linked to Penn in 2014, and confirmed their relationship that summer. In a recent interview, Theron said that Penn was the love of her life and her romance with him was a priority although her career had been demanding.

Reasons for the unfortunate Penn-Theron breakup have yet to be revealed, but in the meantime, we can reflect on some other notable splits which left lovers in the dust this year. Among the most prominent reasons for celebrity breakups are distance and work, although some were more dramatic than others. Here are five of the most significant celebrity breakups of the first half of 2015:

Louis Tomlinson and Eleanor Calder

The One Direction heartthrob ended things with his girlfriend of three years, Eleanor Calder, in early March. News of the split didn't emerge until rumors that the band member had been kissing someone else started forming. Tomlinson and Calder had grown apart due to Tomlinson's frequent touring with the band, which had him away for 9 months at a time, putting tension on the relationship. Calder reportedly attended university in Manchester while her then-boyfriend traveled the globe. The couple failed to announce their breakup until the singer's rep broke the news two weeks afterward.

"They wanted some privacy during this time," the rep said.

Jason Dufner and Amanda Dufner

It was discovered that the only married couple on our list, Jason Dufner and Amanda Dufner, were filing for divorce in late March when a golf website obtained documents proving the separation. The PGA professional's wife filed settlement papers citing "irretrievable breakdown of the marriage" and a "complete incompatibility of temperament that the parties can no longer live together." Their divorce was finalized in April.

The Dufners both had massive social media followings during their marriage, USA Today reports. They split after just three years of marriage and intentionally kept the details of their split away from the media. Afterward, Jason Dufner spent two months giving the media the cold shoulder but warmed back up in early June after a good bout of golfing at the Memorial Tournament.

Tiger Woods and Lindsey Vonn

One of the power-couples of the sports world, golfer Tiger Woods and Olympic skier Lindsey Vonn, went their separate ways in early May. The aftermath wasn't pretty, at least for Woods, as he admitted during a press conference that he was unable to sleep days after the split. In similar messages to their fans, the athletes blamed "hectic" lives and lack of quality time as their reasons for moving forward alone after three years together.

"She has been amazing with Sam [daughter] and Charlie [son] and my entire family," Woods wrote in his statement at the time. "Unfortunately, we lead very hectic lives and are both competing in demanding sports. It's difficult to spend time together."

Chris Soules and Whitney Bischoff

Just 11, weeks after Chris Soules asked for Whitney Bischoff's hand in marriage on The Bachelor, the couple called it quits, breaking their engagement in May. Soules' rep said that the two have nothing but respect for each other and plan to remain friends. In an interview after the breakup, Soules admitted that being on the show altered his actions, although the engagement was indeed real. "I think the whole experience itself lends itself to like making you feel like you want to [get engaged]," he said on the Dan Patrick show June 16. "It's a really weird experience and it's hard to explain unless you've been through it."

Just a few weeks after the reality show's season 19 finale, Bischoff reportedly moved to Soules' farm, but has since moved back to her home in Chicago. "She's a great person and she'll be a friend for the rest of my life," Soules said of his ex-fiance. "Just didn't work out. It was two people that were mature and went into a weird situation, came out, tried to make it work..."

Nick Jonas and Olivia Culpo

The youngest Jo-Bro and former Miss Universe split up in June after 2 years together. Jonas wrote his chart-topping hit "Jealous" about his passion towards Culpo, but obviously his feelings have shifted. After the breakup, Culpo was reportedly heartbroken while Jonas was spotted eating alone in New York City.

In an interview before the breakup, Jonas told ABC News that being in a long-distance relationship with Culpo was "tough" and "interesting" but that it was "all good." He has been extremely busy this summer, performing almost non-stop and even replacing Iggy Azalea last-minute at a Pittsburgh Pride event.