Calvin Klein's Ex-Boyfriend Nick Gruber -- Out of Rehab & Kissing a Chick!

Since getting arrested for cocaine possession and checking into rehab earlier this year, fashion mogul Calvin Klein's ex-boyfriend Nick Gruber has really changed his ways .... he's now sucking face with chicks.

The 22-year-old former gay porn star was spotted holding hands and kissing Chelsea Heath -- who is female -- on the beach in Marina del Rey this weekend.

Just like CK One, Nick is for men and women.