Louis Tomlimson and girlfriend Eleanor Calder split after he reportedly cheated on her with a mystery girl at the sidelines of the One Direction concert in Thailand last week.

That mystery girl turned out to be Lucy Julian, 20, the daughter of designer Alexander Julian, alleged the new report from Daily Mail.

It didn't take long for her Instagram to be flooded with hate messages for allegedly causing the Louis Tomlimson and Eleanor Calder split.

A fan of One Direction wrote in one of Lucy Julian's posts, "Y did u ruin. El and lou's relationship!!!!!JUST Y????? YOU COULDN'T. GET YOUR. OWN SO YOU HAD TO TAKE SOMEONE. ELSES UGH U DISGUST."

In another post, one fan commented, "Can't believe Louis left Eleanor for this ugly chick."

Another fan added, "...I miss Eleanor and eleanor is much prettier than this girl."

An insider told The Sun that Louis Tomlimson and a mystery girl were very cozy together at the Sukothai Hotel.

"Louis and the girl were kissing on and off for about 15 minutes. Louis was just wearing his boxers, having stripped off to swim. They were snogging passionately. I thought it was Eleanor until she turned round. He is going to be in a bit of trouble," the source added.

It was only later that confirmation emerged about the Louis Tomlimon and Eleanor Calder split, with a spokesperson saying, "'Louis and Eleanor split up two weeks ago. They have not announced this as they wanted some privacy during this time."

The Mirror also claimed that the couple tried to work things out prior to the split as Eleanor Calder even flew to Sydney to be with Louis Tomlimson. Their efforts were in vain, however.

"His rep went on to confirm he and Eleanor, who dated for four years, had split two weeks previously and he was single when he cosied up the young woman," the London publication said.