David Burtka & Neil Patrick Harris. Picture: Instagram

Neil Patrick Harris has gushed over his husband David Burtka in a heartfelt tribute on social media to mark their three-year wedding anniversary.

The 44-year-old actor tied the knot with the 42-year-old actor in 2014 in Italy, and on Wednesday (06.09.17) the 'Gone Girl' star took to social media to pen a heartfelt note to his partner, which saw him thank David for "choosing" and "challenging" him throughout their marriage and for starting a family with him. 

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The 'How I Met Your Mother' star - who has twins Harper and Gideon, both six years old, with David - posted an image of the couple on their wedding day to his Instagram account. He captioned the post: "I got married three years ago today. Thanks, David, for choosing me. For challenging me. For creating a family with me. (sic)."

The American star also credited his spouse as being "a safe space that [he] can call home", before he went on to thank David for his "bountiful love" in the celebratory message.

He continued: "For being a safe space that I can call home. And for your bountiful love. Happy Anniversary. @dbelicious (sic)."

But Neil was not the only one to publicly declare his affection on their special day, as the '24 Nights' star also gushed about his lover, which saw him describe the moment their said their nuptials as "the best decision of [his] life". 

David uploaded a collage, which included images of the pair kissing, to his Instagram account, and he captioned the post: "I made the best decision of my life three years ago today. Thank you @nph for saying I do. (sic)."

And David has credited Neil for his "love, strength and dedication" to their family and for making him a "better man". 

He continued: "Your love, strength and dedication to our family is unprecedented. You have made me a better man. Thank you. (sic)."