"S.W.A.T." star Peter Facinelli may be getting serious with girlfriend Lily Anne Harrison, because they just spent the week soaking up the sun in Mexico with her dad.

Facinelli and Harrison vacationed in the Presidential Suite at the Grand Fiesta Americana Coral Beach in Cancún. He brought along his three daughters, and also his sister's family.

He also brought Harrison's father, 67-year-old Gregory Harrison. Gregory is a pretty famous guy, too, he starred in "North Shore" back in the 80s as Chandler.

The brood was treated to pampering at the resort's Hydro Spa, a catamaran excursion to Isla Mujeres for snorkeling and a private dinner at the upscale Mexican eatery, La Joya.

Sources at dinner tell The Blast 44-year-old Facinelli was showering his girlfriend's father with praise and kept hinting at big things to come in the new year.

We're told the vibe among the group was that things between the couple are getting very serious.

Jennie Garth's ex-husband has been dating the 28-year-old actress since late 2016, following his split from Jaimie Alexander.

Hola. From Mexico. #cancun @grandcoralbeach Best start to a New Year with #family

A post shared by Peter Facinelli (@peterfacinelli) on Jan 3, 2018 at 12:57pm PST

Peter Facinelli

Peter Facinelli Gets Cozy in Cancún with Girlfriend ... and Her Father