Ronda Rousey Is So Freakin' Sad ... But Still Honoring America

This is as down in the dumps as we've ever seen Ronda Rousey -- expressing legitimate sadness about her loss to Holly Holm, but also putting on a brave face ... for the Marines!

Ronda was up super early Friday morning to travel to tonight's Marine Corps Ball ... remember, before her UFC defeat ... Rousey accepted Lance Corporal Jarrod Haschert's invite.

It's been a month, but she admits she'd probably be on the couch "crying and eating ice cream" if she hadn't committed to the ball -- but you can tell she's honored to be going.

There's more ... she talks about the rematch and her next movie. Interesting, her bf Travis Browne is there sending her off.

She's in your hands now, Lance Corporal Haschert.