Ethan Slater Flies Solo For First Event After Ariana Grande Split

Ethan Slater is stepping out in public for the first time since we broke the news he and Ariana Grande called it quits ... and he's on a solo mission.

The "Wicked" star put on a brave face Thursday, attending Shakespeare in the Park's production of "Romeo & Juliet" at The Delacorte Theater in New York City's Central Park.

Ethan kept it casual amid high temperatures in the Big Apple ... opting for a white T-shirt, black slacks and white sneakers paired with a silver chain.

We told you about Ethan and Ariana's shocking split Monday ... with our sources revealing they quietly parted ways in recent months and that it was "amicable."

The news came after Ariana kicked off her "Eternal Sunshine" tour Saturday night in Oakland, California -- her first tour in 7 years. We're told her latest album is not inspired by the breakup at all.

As you know, Ariana and Ethan met on the set of "Wicked" ... and eyebrows were raised when they exited their respective marriages around the same time and then got together.

The pair kept a low profile on their relationship ... and now, Ariana can say "thank u, next."