Heidi Klum & Seal – Kiss Me Goodbye ... As My Girlfriend Watches (PHOTO)

Heidi Klum got a goodbye kiss from ex-hubby Seal Sunday night, which wouldn’t have been awkward if Seal’s new girlfriend Erica Packer hadn’t been watching intently.

The former couple took their 4 kids – Leni, Henry, Johan, Lou – to Nobu in NYC for dinner, but added a few more seats to the table, including one for Packer, the ex-wife of Mariah Carey's billionaire BF, James Packer.

It's the first time Erica's been spotted with Seal's brood.

Kind of reminds you of those "Kiss From A Rose" lyrics ... "Ooh, the more I get of you, The stranger it feels, yeah."