Jennie Garth Engaged to David Abrams

When David Abrams Tweeted a happy birthday message to Jennie Garth on April 3, the writing – or hashtag – was clearly on the wall: #loveumoreandmoreeachday.

Indeed, the Mystery Girls star, 43, and Abrams are engaged, the actors’ reps confirm to PEOPLE exclusively.

“Dave had been working on this for months, and really wanted to plan something special for her around her birthday and make it perfect,” a source close to the couple says.

The smitten stars have been inseparable since last fall.

In early March, they spent a romantic weekend in Santa Barbara, California, and recently enjoyed a sun-drenched vacation in Tulum, Mexico, with Garth’s three daughters.

Abrams Tweeted a photo from a hike in Santa Barbara, captioning it, “Our selfie game is strong.”

This will be Garth’s third marriage: She has daughters Luca, 17, Lola, 12, and Fiona, 8, with her ex-husband, Twilight actor Peter Facinelli. She was also married to Daniel B. Clark.