Taylor Swift and Calvin Harris celebrate one-year anniversary

He’s a keeper.

Taylor Swift took to Instagram Sunday to share the sweet treasure Calvin Harris gifted her for their one-year anniversary.

“3.6.15 One year down!” the 26-year-old singer captioned a gold locket engraved with the special date.

Not to be outdone by his social savvy gal pal, Harris, 32, posted a clip on Snapchat featuring a chocolate frosted cake with the words “1 Year” written beside two red hearts, as well as a smitten Swift standing nearby.

“Calvin knows that Taylor is the woman for him,” a source told E! News. “Out of all of Calvin’s relationships, he seems the happiest with Taylor. He always says to all of his friends that Taylor is marriage material.”

Swift and Harris made their debut as a couple last summer, lounging poolside aboard an inflatable swan. And while they’ve each made cameo appearances on one another’s social feeds, Harris’ sincere sentiment following Swift’s win for Album of the Year at the Grammys last month stands out.

“Congratulations to my beautiful girlfriend,” Harris wrote on Instagram.

Before Harris showered Swift with gifts over the weekend, the pair enjoyed a pre-anniversary dinner at CUT in Beverly Hills on Tuesday.