Alex de Minaur sent a heartfelt message to his girlfriend after her Hong Kong Open loss.
The British No. 1 had never lost a final before but she was thrashed by top seed Diana Shnaider.
Boulter still ended the year on a positive note though, reaching a career-high ranking, and her partner was one of the first to celebrate.
Boulter has been putting in the work at the end of the WTA Tour season, spending seven weeks on the road for the Asian swing. Her efforts were rewarded when she reached the Tokyo semi-final.
And she went one better in Hong Kong - her last regular singles event of the year - by reaching the final. The 28-year-old had a 3-0 record in WTA finals going into Sunday's championship match.
But Shnaider ended her streak, needing 71 minutes to beat Boulter 6-1 6-2. While it was a heartbreaking defeat for Boulter, she was still rewarded with a career-high ranking of No. 23 in the world.
The Brit took to Instagram to reflect on her Asian swing. "Not the one I wanted," she wrote with a crying emoji.
"But proud of my head and fight this week. 7 weeks later and I can finally go home. Thank you Asian and @hk_tennisopen for making it feel like home."
And her boyfriend, ATP No. 8 De Minaur, was one of the first to congratulate Boulter on her impressive run. "So proud of you," he wrote alongside a heart-eye emoji and a love heart. "New career high."
Boulter will be back in action later this month to represent Britain in the Billie Jean King Cup Finals but her 2024 WTA season has come to an end. It saw her pick up two titles - she defended her Nottingham crown and won her biggest tournament yet at the WTA 500 in San Diego.
After losing to Shnaider on Sunday, the new world No. 23 said: "I would be worried if was on week seven in Asia, at the very end of a season and I didn't have an empty tank, as it would mean I am doing something wrong all year round.
"I came out here and wanted to push myself playing this tournament, and just to play more weeks in a row, it is not something I do very often, especually body-wise.
"I am here with a strong body, an empty tank but I am happy as I pushed my boundaries this week and that is what is going to make me stronger and tougher as a tennis player and hopefully if I am going to reach higher ranking points, then it is going to take me to those places."
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