Warning! Spoilers ahead for Thor: Love and Thunder

Thor: Ragnarok. While the real-life reason has to do with director Taika Waititi breathing new life into the franchise with the third installment, released in 2017, key flashbacks in the fourth Thor movie have provided the in-universe reasons for the Son of Odin's personality changes and increased humor, and much of it has to do with Thor's ex-girlfriend Jane Foster.

As seen in Thor: Love and Thunder, Jane Foster is the new wielder of a reforged Mjölnir, becoming the Mighty Thor as an honorary Asgardian. This leads to Thor and Jane's reunion as they take on Avengers: Age of Ultron, it's been years since Thor and Jane were an item.

Related:  Thor: Love And Thunder Fixed The MCU's Jane Problem

Thankfully, Thor: Love and Thunder provides flashbacks that cover the time when Thor and Jane were a couple between films. As such, these moments are crucial to understanding why the Odinson of the first two Thor movies is so much different compared to the one seen in Thor: Ragnarok and since. Here are the biggest changes Thor underwent as a character as well as Jane's role in his overall evolution as the Mightiest Avenger.

Ragnarok's Thor Was A Very Different God Of Thunder

Thor Hulk and Valkyrie On Sakaar In Thor Ragnarok

While all of Thor: The Dark World).

Taika Waititi turned Thor into one of Marvel's most popular heroes with Thor: Ragnarok. Suddenly, Thor was extremely funny. He was more laid back, with the Shakespearean language he was mocked for by Iron Man in earlier films lessened. Combined with Thor embracing his full power as the God of Thunder, Thor: Ragnarok is often cited as one of the best MCU movies of all time. Clearly, Thor's drastic new change was successful, but what caused it? Despite being on Earth ever so briefly to meet Doctor Strange and find his father Odin, Thor had become much more "human."

How Love and Thunder Explains Thor's Big Character Changes

Thor and Jane looking at each other in Thor Love and Thunder

Thor: Love and Thunder confirms that Thor's relationship with Jane Foster is what brought on his evolution between films. Narrated by Korg, the flashbacks feature Thor and Jane living together on Earth before they eventually drifted apart prior to Thor: Ragnarok. With scenes depicting the couple rollerblading, going to restaurants, and attending costume parties together (where the Odinson is dressed as a giant hot dog), Korg confirms that Thor taught Jane the way of the warrior while she taught the God of Thunder how to be more human.

Related: What Does Jane Whisper To Thor At The End Of Love & Thunder?

These flashbacks with Jane between Dark World and Love and Thunder help make Thor's changes far less drastic than they were prior to this latest Thor adventure. Jane was why Thor learned humility and comion in the very first Thor. It makes sense that she would continue to be the reason for his continued growth and evolution into a more relatable hero, becoming one of the most "human" gods in the entire MCU. While elements of this were likely assumed by those looking to fill in the gaps of Thor's journey, it's good that Thor: Love and Thunder outright confirms why the Son of Odin has changed so much over time — going beyond Marvel's need to overhaul the hero with Watiti at the helm.

Want more Thor: Love and Thunder articles? Check out our essential content below...

More: Cutting 1 Love & Thunder Scene Makes Mighty Thor's Origin Way Better