The popular television show Portlandia depicts the city of Portland, Oregon as a hipster haven of indie book shops and artisanal coffee, but for many, those quirks can’t compare to the buzzing activity of bigger cities.

As it turns out, that was the simple problem for Nike’s young star CIO Anthony Watson.

When news broke Wednesday evening that the 38-year-old executive had left the company after only 10 months in the position, news outlets were puzzled. Nike would only say, through a company statement, “Anthony Watson has left Nike Inc. for personal reasons.”

Late Wednesday night, in three posts on Twitter, Watson said the same, in a bit warmer fashion, while refusing to get specific. “Thank you for all the enquiries,” he tweeted. “Today I left Nike for personal reasons. There is honestly nothing ‘mysterious’ about my departure… Nike is a great company, with amazing people. It’s just my personal circumstances changed… My leaving has nothing to do with Nike or any vendor. I wish Nike every success for the future. It’s a wonderful company.”

Now, a source close to the situation has told Fortune the precise reason for Watson’s departure: though he was happy with his job, he was unhappy with the social scene (or lack thereof) in Portland. “As a single gay guy from London,” the source says, Watson “underestimated what it would be like. It was a culture shock. And there’s no point in having a great job if you feel unhappy with your surroundings.” The decision to leave the shoe giant crystalized for Watson while home in London with his family over the Thanksgiving break.

The young executive, who is openly gay and actively involved in GLAAD, came to Nike NKE in April of this year from Barclays, where he was CIO of Europe, Middle East, and its global operations. There, he helped make the bank more nimble from a tech standpoint. Under his guidance it put out a number of new mobile apps.

In 2013 Watson became the first non-U.S. citizen to join the board of GLAAD. His new role at Nike also made him one of the first openly gay C-suite executives at a Fortune 500 company. Last fall, Watson landed at no. 19 on the Fortune 40 Under 40 list.

In Oregon, he dove in right away and helped the sports apparel giant sign a big deal with Juniper Networks as a new network vendor. He leaves after the completion of a new five-year road map for I.T. strategy at the $27.8 billion-in-sales behemoth.

In an internal Nike memo obtained by Fortune, COO Eric Sprunk explained Watson’s departure to employees: “Anthony Watson is leaving Nike for personal reasons. During his time at Nike, Anthony worked on a vision and five-year strategy to reset Technology as a critical platform for Nike’s growth. I’d like to personally thank Anthony for his contributions… While we work to identify Anthony’s replacement, I will step in immediately to lead the Tech organization. I am confident we will continue to deliver high impact results and appreciate your support during this transition.”