McIlroy was spotted leaving the Loggerhead sanctuary in Juno Beach, FL. with his fam by his side -- and while it seems they had a good day looking at sea creatures ... it's not hard to see the 35-year-old athlete still appears to be reeling from his Sunday meltdown.

Check out some footage of the McIlroys as they left their day date by the ocean ... while Mom and Daughter looked content holding some goodies from the building, McIlory was noticeably skulking feet behind.

Of course, it's hard to blame Rory for the long face ... after all, he had control of the major golf event over the weekend -- but fumbled it to Bryson DeChambeau after missing a pair of what looked like gimme putts down the stretch.

However, while his game on the course clearly needs a bit more refinement ... it at least seems everything's getting better back at home.

You'll recall, Rory filed for divorce from Erica last month -- but had an apparent change of heart days before the U.S. Open kicked off last week. Both Rory and Erica were rockin' their wedding rings -- a good sign that they're well on their way to mending their issues.