The former Beverly Hills, 90210 star began dating Abrams last autumn (14) and he proposed this month (Apr15) during her 43rd birthday celebrations, a representative for the couple confirms to

A source says, "Dave had been working on this for months, and really wanted to plan something special for her around her birthday and make it perfect."

Garth was previously married to Twilight actor Peter Facinelli from 2001 to 2013. They have three daughters, Luca, 17, Lola, 12, and Fiona, eight.

Facinelli is also newly engaged - he popped the question to Thor actress Jaimie Alexander last month (Mar15).