The couple announced their engagement in April after they initially sparked romance rumours last January.
In a recent episode of his podcast, Life is Short, the 44-year-old recalled working on horror film Barbarian in Bulgaria and revealed that he began to “really fall in love” with Bosworth during the shoot.
He shared: “I was there while I was like really falling in love with my now-wife.
“She came to visit, and I had never been comfortable with… set visits. I like to separate the relationship... But, yeah, I loved having her there and we just had the most magical time.
“It helped me having her there. She’d help me with scenes. It was the best.”
Meanwhile, Bosworth, 40, raised eyebrows earlier this week when she was spotted wearing what appeared to be a wedding ring with her engagement ring on a recent Amazon Live video with Long.
The Standard has contacted Justin Long and Kate Bosworth’s reps for comment.
Last month, the couple opened up about their engagement on Long’s podcast after speculation began when Bosworth, 40, was spotted wearing an engagement ring at the Vanity Fair Oscars Party.
Long revealed he had planned a “special thing” around Bosworth’s 40th birthday in January, but that around a month before personal circumstances had thrown them off course.
“Things change, and sometimes they change pretty drastically without any warnings,” the Jeepers Creepers actor said.
The Blue Crush actress added that they had “just gone through this really hard thing and we had spoken to a therapist”.
“We were trying to move through things at the time and she gave us a really great piece of advice which was, ‘Make sure that you’re pretty consistently asking the other what you need, or asking the other what they need’,” she recalled.
“I remember waking up not so many mornings after that therapy session and I looked at Justin… I smiled at you, and I said, ‘What do you need?’
“And he really looked at me and he said, ‘To spend my life with you’. And I smiled and I said, ‘Well, yeah, you have that. Oh my gosh, you have that’, and he said, ‘No, I mean I really want to spend my life with you’.”
Long admitted: “The words just came out so naturally.”
Reflecting on the moment, Bosworth said: “I thought it was the most romantic and honest and loving proposal.”
The couple also posted a series of photos to their Instagram accounts to announce the podcast and tease the happy news.