Kourtney Kardashian arrived back in L.A. ... but zipped it shut when photogs asked about all the hoopla over her baby daddy.
Kourtney and Scott Disick were minutes apart from each other in Cannes -- her with BF Younes Bendjima -- and him for a hot minute with 19-year-old Bella Thorne.
Kourtney and Scott are not getting along -- which is an understatement -- but she didn't play her hand at LAX.
Ditto for 'lil sis Kendall Jenner, who also kept it shut.