Younes Bendjima Plays Dad with Kourtney Kardashian's Son in Italy

Kourtney Kardashian and Younes Bendjima are continuing their vacation overseas, and her children have joined them ... so Kourt's 24-year-old boyfriend is taking on some daddy duties.

The couple was spotted out on a boat in Portofino, Italy Saturday with Kourt's 3-year-old son Reign -- her youngest of 3 kids with Scott Disick -- and Younes looks pretty natural in the role of protective parent.

As we reported ... Younes and Kourtney were on a private boat last week in Capri -- just the 2 of them -- showing off their hot bods while soaking up the sun.