Josh Brolin has got engaged

Brolin is said to have popped the question two months ago, having celebrated their engagement with a group of pals while on a romantic holiday in Cabo San Lucas, Mexico earlier this month.

A source told Us Weekly: "They were with two tables worth of people so it was a big group, more than eight people. They had a fixed menu and it seemed like they were celebrating something ... It looked like a party and it seemed celebratory."

Brolin and his assistant were said to be "all over each other" on the night, with Boyd apparently "sitting on his lap" throughout the dinner.

The eyewitness added: "They were kissing each other a lot, had their arms around each other. Super affectionate all night."

The couple are believed to have begun dating in March 2013, just one month after representatives for both Brolin and his ex-wife Diane Lane revealed they were filing for divorce after eight years of marriage.

However, they weren't seen showing off their romance until February 2014, when they were spotted kissing and cuddling while on a trip to Rome.

The 47-year-old actor was also previously married to 'Beverly Hills Cop II' actress Alice Adair, with whom he has children Trevor, 26, and Eden, 20.