Detroit Tigers pitcher Jack Flaherty suffered a disappointment in his professional life after losing Game 5 of the ALDS to the Seattle Mariners on Friday. Almost a week later, he had reason to celebrate off the mound.Flaherty turned 30 on Wednesday, and his girlfriend, Katie Johnson, shared a sweet message for him on the special occasion. She shared a multi-snap post on Instagram, with the cover image showing a silhouette of Flaherty walking on a beach at sunset. He wore a baseball cap and carried a pair of shoes. In the background, the sun set over the ocean, creating an orange and yellow glow in the sky."Three decades of Jack. And I get the best one 🫶🏼 Happy birthday to my favorite person. I love you," Johnson captioned the post. View this post on Instagram Instagram PostFlaherty appeared to have been caught off guard by the post."I’m going to act like you didn’t post that video and photo," he commented.Jack Flaherty's comment [Image Source: Instagram/katieajohnson]The video showed Flaherty walking inside his home, with the laughter of a woman, presumably Johnson, audible in the background. The image mentioned by Flaherty was likely the one showing him lying on his back, wearing a collagen mask.Flaherty's girlfriend's birthday post also featured images of the couple. The second image showed Flaherty embracing Johnson by a swimming pool, while another picture was a candid snap of the couple taken immediately after an MLB game.Partners of Tigers players wish Jack Flaherty on his birthdayJack Flaherty joined the Detroit Tigers on a two-year, $35,000,000 contract in February. Flaherty had spent the beginning of the previous season with the Tigers before the Dodgers acquired him in a trade.After Katie Johnson's sweet birthday post on Instagram, many sent well wishes to Flaherty."Happy bday Jack!!!🥳," Riley Green's girlfriend, Alison Bloomquist, wrote."🤍🎉 hbd Jack🎉!!" Zach McKinstry's wife, Karra, said."collagen mask slay! happy bday Jack!" Brenan Hanifee's wife, Cana, commented.Screenshot of comments [Image Source: Instagram/katieajohnson]Greene, selected by the Tigers in the 2019 MLB draft, has been playing for the team since 2022. He has two All-Star selections. McKinstry joined the Tigers in 2023. He earned his first All-Star selection this year. Hanifee, a 2016 draft pick, debuted in 2023.