He spoke out in support of his significant other amid the new doco - which delves into the 39-year-old star's rise to fame, as well as her subsequent mental health and legal struggles, and her conservatorship - and says he will strive to give Britney the future she "wants and deserves".
He told People: "I have always wanted nothing but the best for my better half, and will continue to support her following her dreams and creating the future she wants and deserves.
"I am thankful for all of the love and support she is receiving from her fans all over the world, and I am looking forward to a normal, amazing future together."
Britney - who met Asghari on the set of her 2016 music video Slumber Party - is not said to have authorised the New York Times Presents documentary.
The Toxic hitmaker hasn't had control of her own affairs since 2008, following her public breakdown.
She is currently locked in a legal battle against her father, Jamie Spears, to have him permanently removed from her conservatorship, as she no longer wants him to have control over her life.
The agreement was extended following numerous hearings in 2020, with the most recent ruling from December leaving it in place until September 2021.
But there are multiple hearings scheduled prior to September, which could alter its structure.
Britney and Asghari have kept their relationship mostly private, but she admitted during the coronavirus pandemic lockdown last April that she was missing him due to quarantining.
She wrote on Instagram: "I have been quarantining since I got back from Louisiana weeks ago ... so basically I haven't seen my boyfriend @samasghari in what feels like a lifetime!!!! (sic)"
And in December, Asghari joked Britney had been celebrating her 39th birthday - which was on December 2 - for the whole of the month.
He quipped: "OK baby, we get it. It's your birthday. We've been celebrating for a month. Let's move on."
- Additional reporting, NZ Herald
