The actor and model became engaged to Spears, 40, last year.
Sharing a photo of the couple together on a beach holiday, Asghari joked: “Most of you think I’m 49 but you’re wrong.”
“I already celebrate every single day for this opportunity called ‘life’,” he continued. “The more mature I become the more I realise that I’m one SOB.”
Meanwhile, on her own Instagram page, Spears shared the image of the pair together, and a post in which she referred to Asghari as her “husband”.
“Happy Birthday to my fiancé,” wrote Spears in the first post, a day before appearing to confirm she had, in fact, married him.
“I love you so much… I want a family with you … I want it all with you !!!!”
In another Instagram post, the artist shared a video of baby turtles crawling their way to the sea.
“My husband @samasghari sent me this and said: ‘100 baby turtles leave the hatch, only 20 make it to reefs because most get eaten by sharks, only 1 strong strong Turtle makes it out of 100 and comes back a year later stronger than ever and hatches babies,’” wrote Spears.
“He said these turtles represented life.”