Why did Lagertha leave Ragnar in Vikings? Explained

In the first episode of season 2 of the television show Vikings, Lagertha (Katheryn Winnick), decides to leave her husband, Ragnar Lothbrok (Travis Fimmel), after he gets another woman pregnant and desires to take her in as his second wife.

Ragnar and Lagertha are perhaps the two most important characters in Vikings, whose relationship, whether it be married or not, played a major role in the narrative. At first, it appeared that the two were a wonderful match, and even when things didn't work out, there was a lingering sense that they might someday get back together.

Ultimately, their chemistry and affection were evident, and even though Lagertha had been in prior relationships and marriages, she didn’t seem to have found another true love the way she did with Ragnar.

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Looking into Lagertha and Ragnar’s separation story in Vikings

Although Ragnar and Lagertha's romance was limited to one season of Vikings, it had a significant impact on the show and was regarded as one of the most significant partnerships of the plot.

Throughout the first season of the show, Lagertha was married to Ragnar, and she moved with him to their new residence after he became the Earl of Kattegat. They had a long history together and were in love. They had two kids, Bjorn (played by Nathan O'Toole) and Gyda (played by Ruby O'Leary). Unfortunately, Gyda passed away in the first season when a pandemic struck Kattegat.

The couple's relationship appeared stable until Lagertha miscarried. Ragnar began to question who would provide him with the several sons that the Seer, played by John Kavanagh, predicted to foresee.

While on an expedition, Ragnar met Aslaug (Alyssa Sutherland) his second wife, who was also a princess from Gotaland. When a plague decimated Kattegat, killing many people including Ragnar and Lagertha's daughter, she was at home reigning on Ragnar's behalf.

Ragnar ended up sleeping with Aslaug while cheating on his wife Lagertha and getting her pregnant in Vikings. Bjorn, who traveled with his father, told his mother enough that she understood that Ragnar cheated. Ragnar then admitted to his unfaithfulness and told her he would never see Aslaug again.

Aslaug then came to Ragnar months later, looking heavily pregnant, and despite having given his wife his word about not seeing Aslaug again, Ragnar couldn’t turn her away as she was carrying his child. Ragnar then suggested having both the women in his life as his wives. Aslaug pretended that she had no objection to the idea, after which Ragner tried to convince Lagertha too.

Lagertha was not willing to share her husband with another woman, and thus decided to leave Kattegat, divorcing her husband. The divorce was painful to watch as it was evident that Ragnar was heartbroken. While his intention was not to prioritize one woman over the other, his lineage was important to him.

Bjorn decided to follow his mother and wasn't seen by Ragnar until four years later. Ragnar moved on with his life, marrying his second wife, Aslaug, and having four sons.

Lagertha headed out and married elsewhere only to reunite in Vikings after four years with Ragnar as ‘Earl Ingstag’ and to fight alongside one another as allies.

Finally, during the fourth season of Vikings, Ragnar gave her a final kiss and expressed his regret for all that transpired, including the destruction of "their" settlement, the breakdown of their marriage, and the loss of their dreams. Although the couple's ending was painful, it acknowledges that they were still regarded as one of the show's most significant couples even if they only separated after one season.