Pamela Anderson and Liam Neeson have been slowly letting their low-key romance all hang out, which just accelerated in a touching moment of PDA on live TV … dropping hints about their fast-developing relationship.

Liam and Pam were guests on “Watch What Happens Live” Sunday night when the two stars shared an intimate moment — involving lip balm — while seated next to each other alongside host Andy Cohen.

Check out the video … Pam, Liam and Andy are talking about Pam’s skincare brand, Sonsi Skin, and Pam pulls out some of her signature lip balm. Pam applies the product to her lower lip, then reaches over and offers it to Liam, who is more than happy to lean in and have Pamster put some gloss on his kisser!

In another segment, “Pillow Talk,” the pair dished separately to host Andy Cohen when he posed the question, “How many times have you each been truly in love?”

Pamela sighed and said after a long pause … “One and a half.” We presume rocker Tommy Lee is the first — seems like her new situationship with Liam is likely halfway there? Time will tell.

Liam confessed his number is two … he was married to actress Natasha Richardson, before her untimely death in 2009. Looks like he may be all in on this new linkage.

Andy also pointed out the possible source of his and Pam’s ongoing onset giggles … hinting Liam’s son Daniel‘s De Nada tequila may have had something to do with it.