Sebastian Stan Says He's 'So Grateful' for Girlfriend Alejandra Onieva in Sweet Birthday Tribute

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Sebastian Stan is giving fans a rare glimpse into his relationship with Spanish actress Alejandra Onieva.

The Falcon and the Winter Solider actor, 38, shared to Instagram this week a hilarious short film, made to celebrate Onieva's birthday (she turned 29 on June 1).

In the video, which Stan appears to have shot himself, he documents his days with Onieva — from their mornings waking up, having coffee, and cooking breakfast, to their romantic date nights.

The only catch in the video? Onieva wasn't in person for any of it! Instead, she appeared the whole time in a photo on Stan's phone.

"Happy Birthday @ale_onieva!!" Stan captioned his post. "Over a year ago, out of a lot of darkness...you became the light 🔥 I'm so grateful 🙏🏻❤️🙏🏻 #2020 #loveinthetimeofcovid #quarantinenights"

Onieva commented on her beau's post, writing, "The love you give me is the most beautiful gift this life has given me, te quiero!"

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Both Stan and Onieva have remained private about their relationship, though Onieva shared a photo of them on her Instagram page in December.

"Walking on a dream," she captioned a pic of her and Stan's shadows at the time.

Lately, Stan has been busy filming for the upcoming Hulu series, Pam & Tommy, in which he plays Tommy Lee opposite Lily James' Pamela Anderson.

RELATED: Everything We Know About Hulu's Pam & Tommy, from the Lookalike Cast to the Dramatic Backstory

In May, the streaming service unveiled a first look at Stan and James' dramatic transformations into Lee and Anderson. "Love bites," Stan captioned the shot on Instagram of James biting his nipple ring, in which the two actors look strikingly similar to their characters.

He recently opened up about the unveiling of his transformation into Lee for the Hulu show, which also stars Seth Rogen, Nick Offerman and Taylor Schilling.

"Honestly, it was freeing, because I was walking around in these hoodies and hats … just paranoid of being seen," he said during an appearance on the Just for Variety podcast. "I was like, 'God, I hope they're finally going to release something so you know what we look like, so we can go on with our lives.'"