Adele's lesson on love is "do as I say, not as I do" -- because she's spilling her guts about the upside of her divorce, while also setting up another innocent couple ... for never-ending love, we're sure.
The singer's got everyone talking love -- the good and bad parts -- after her "Adele One Night Only" special aired Sunday night ... it featured an interview with Oprah, and a scenic concert filmed at L.A.'s Griffith Observatory.
That being said, Adele proved she's still a sucker for love by helping a guy named Quentin pull off a surprise marriage proposal to his GF, Ashley, in the middle of her concert.
She told the crowd, "I'm a bit nervous in case it doesn't go well. It's also a bit ironic that I'm letting this happen" ... clearly referencing her divorce.
Needless to say, it all went well -- Ashley said yes and was genuinely shocked as hell when Adele suddenly appeared in front of them, and joked ... "Thank God she said yes, 'cause I didn't know who I was going to have to sing this song to next, you or him. Oh, my God, look at her she's so in shock."
Then she serenaded them with "Make You Feel My Love." Very cool moment ... if you're the rom-com type.
Anyway, the 15-time Grammy winner also belted out hits like "Hello," “Someone Like You” and her current No. 1 single “Easy on Me.”