Now you know it's gotta be real ... 49ers QB Jimmy Garoppolo has been seen with his new girlfriend at the ONE place you only take a serious relationship -- DISNEYLAND.

ICYMI -- Alexandra King posted a picture of the couple on social media back in February ... but since Jimmy has yet to put it on the 'Gram himself, people have been wondering what's going on.

Wonder no more, 'cause the couple was spotted at the Happiest Place on Earth riding rides, playing games and holding hands together ... ya know, real cute stuff.

We here at TMZ Sports would like to apologize to all the ladies (and some of you fellas) who will be heartbroken by these pictures, but in times like this you have to remember one thing.