Rob Kardashian & Blac Chyna Kiss On Cam, But ... Where's the Love???

Blac Chyna finally planted her lips on Rob Kardashian for everyone to see, but something might be missing here.

Considering Rob and Chyna have been almost inseparable for about a month now -- you'd probably expect something more passionate than a BFF-like peck on the cheek for their first Instagram kiss.

No doubt, BC's been great for Rob's confidence and his workout regimen, but c'mon -- where is the love? Where's the passion?

On the other hand ... this is the happiest we've seen Rob in years.