Megan Fox and Machine Gun Kelly Discussed Getting Engaged for 'a While': Source

Megan Fox and Machine Gun Kelly's engagement was no shock to their friends.

A source close to the newly engaged couple tells PEOPLE that "nobody was surprised" when MGK, 31, popped the question to Fox, 35, last week during a Puerto Rican vacation.

"They had been talking about it for a while," the insider says.

"For those two, it was very much a love at first sight situation. They spend every waking second together," the source adds. "They are always together for each other's professional and personal events."

"She always likes to be by his side. All of his friends and colleagues know that if they're going somewhere, nine out of ten times, Megan will be there."

Fox announced their engagement last Wednesday on Instagram, sharing a video of the Born with Horns artist getting down on one knee under a banyan tree, which holds a significant meaning in their relationship.

"In July of 2020 we sat under this banyan tree. We asked for magic. We were oblivious to the pain we would face together in such a short, frenetic period of time," she captioned the clip. "Unaware of the work and sacrifices the relationship would require from us but intoxicated off of the love. And the karma."

"Somehow a year and a half later, having walked through hell together, and having laughed more than I ever imagined possible, he asked me to marry him. And just as in every lifetime before this one, and as in every lifetime that will follow it, I said yes. … and then we drank each other's blood 1.11.22," Fox wrote.

RELATED VIDEO: Megan Fox and Machine Gun Kelly Are Engaged!

Although their friends saw it coming, another source previously told PEOPLE that it "was a surprise" to Fox, who "loved the proposal" and "thought it was beautiful and perfect," adding: "She is excited to get married."

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Fox met Kelly while filming the movie Midnight in the Switchgrass in early 2020. The pair made their relationship Instagram official that summer after she appeared in his "Bloody Valentine" music video.

The video came just days after Fox's husband of almost 10 years, Brian Austin Green, 48, confirmed their split. She and Green co-parent sons Noah Shannon, 9, Bodhi Ransom, 7, and Journey River, 5. Kelly shares 12-year-old daughter Casie Colson with ex Emma Cannon.