Along with the heartfelt message, Tiffany, who is the youngest daughter of the president, shared a beachside shot of the sunglass-wearing couple smiling for the camera.
“Happy Birthday, @michaelboulos 🎈❤️🎈You fill my life with so much joy, kindness and laughter!” she wrote in the caption of the shot. “Thank you for always putting a smile on my face! ♥︎”
Tiffany and Michael made their relationship Instagram official in December, but the pair have known each other since summer 2017.
A source confirmed to PEOPLE that they first met over the summer in Mykonos, Greece, at Lindsay Lohan‘s Beach Club, which is the subject of the MTV reality show with the selfsame title, Lindsay Lohan’s Beach Club.
Last September, Michael and Tiffany were spotted sitting next to each other at a Taoray Wang show during New York Fashion Week and by December, the globe-trotting businessman had shared a Christmas photo with his girlfriend on his Instagram.
Since then, the couple have been nearly inseparable, with photos all over their respective social media accounts, including a recent trip to New York City and one with Donald, 73, at his Mar-a-Lago golf resort.
While Tiffany was celebrating her boyfriend’s birthday, her father was returning from his time in France for the G7 summit last weekend.
The president wrapped the summit on Monday with a wide-ranging news conference that covered everything from his desire to host next year’s sit-down of world leaders at his own Miami golf resort to his dismissal of climate change solutions as nothing but “dreams.”
Trump spoke at the Hôtel du Palais in Biarritz and sang the praises of his very own Trump National Doral Golf Club, where he expressed interest in hosting Canada, France, Germany, the United Kingdom, Japan and Italy next year.
Though he has turned over daily operations of his eponymous real estate company to his family, Trump retains his ownership stake — and the profits that his properties make.
The president had brought up his club during a meeting with German Chancellor Angela Merkel and again declared his intent to host during Monday’s presser, claiming Dorral’s close proximity to airports made it a prime contender and reassured that he was not looking to make money from the presidency.
Later on, the president, who is a longtime skeptic of alternative energy (and windmills), also talked about climate change after skipping an earlier session on the topic, which a spokeswoman blamed on conflicting schedules.
“I feel that the United States has tremendous wealth,” he said. “We are now the No. 1 energy producer in the world, and soon it will be by far … I’m not going to lose that wealth on dreams, on windmills, which, frankly, aren’t working too well.”
Trump falsely claimed back in April that noise produced by windmills “causes cancer,” though a 2014 report from the National Institutes of Health that found wind turbines were not related to adverse health.
The president on Monday declared himself an “environmentalist” despite past actions to the contrary, including his withdrawal from the Paris climate agreement and a tweet that once declared global warming as having been created by China.
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“I think I know more about the environment than most people,” he boasted.
Elsewhere in his news conference, Trump mentioned how he hopes to see Russia return to the G7 following its 2014 removal over the annexation of Crimea. He had reportedly expressed his view with other G7 leaders, several of whom responded with their concerns about Russia’s autocratic behavior — at odds with G7’s democratic values.
“Is it good? Probably not. Maybe it is,” Trump said of the possibility of a Russian return. “A lot of people say having Russia — which is a power — having them inside the room is better than having them outside the room.”