Chappell Roan ain't hitting up the "Pink Pony Club" solo anymore ... and, she hasn't been for a while apparently -- 'cause she's going steady with someone!

The singer-songwriter stopped by Alex Cooper's "Call Her Daddy" podcast ... and casually dropped she's dating someone -- admitting they've been together for about 6 months.

Roan adds it's not a casual fling, but instead a super serious 'ship ... so, sounds like CR's locked up.

Chappell says despite her relationship status, she had a great time as a single person ... and, she recommends people learn whether they can be comfortable on their own before they try to get into a relationship.

As for how Roan can even begin dating someone given her level of stardom ... she says that's not a problem she's had to deal with yet -- 'cause she actually met this woman before she blew up, so her fame couldn't have played a factor in their romance.

Worth noting ... we haven't seen Chappell at any red-carpet events with anyone -- so, clearly she and her better half aren't ready to step into the limelight as a couple yet. However, back in September, she did seemingly tease this relationship to Rolling Stone ... saying she couldn't commit to anyone because she felt like no one could understand her.

Roan says in the interview, “She’s so awesome and so secure in herself and [has told me] ‘No pressure, we can just be friends if you want.' I’m just running around like a chicken with my head cut off. I’m just like, ‘What? I can’t get married!’ It is that type of delusion right now.”

Chappell dives deeper into marriage on 'CHD' ... saying she doesn't know if or when she'll get married and have kids -- admitting the political climate makes planning a future more difficult.