Since Bitterbat and Sweetheart are based of off those old tropes of "villain with a crush on the magical girl" and those series' tended to have a very plain and vanilla "good boy" for the magical girl as well, was there anyone like that for a young Sweetheart? And more importantly, how badly did Bitterbat kick his ass?
That would be the Blue Elephant aka Gabe aka Angel's brother.
Sweetheart and Bitterbat had been crushing on each other for ages although Sweetie was def aware it wasn't appropriate for their alignments. But the heart wants what the heart wants.
That didn't mean she didn't try to disobey her heart and force her feelings toward someone else via going on a solo hang out with Gabe...which didn't work. It was awkward because there was just no romantic feelings. Bitterbat of course crashed the date but they both were very thankful it.
Gabe never had a crush on Sweetheart and viewed her only as a friend and the feeling was mutual. He was one of the few aware of Sweetheart's feelings for Bitterbat even if she never shared them out loud because she'd always get this sparkle in her eyes when she fought him that def did not look like hate.
As for Bitterbat kicking his ass, the closest he got was that very hang out session because it looked (and was meant to be a date) and welp...the concept of Sweetheart being with someone else made him a bit looney. Tho that was mainly because he could sense her love for him (that's lore to ramble about for another day tho...or ask. Whatever comes first)
Thankfully, Sweetheart managed to calm him down so Gabe never got hurt.
Now and days, Sweetheart and Gabe are best buds. He knew how much she loved Bitterbat and how hard their separation was so he kept in contact when the Beloveds were still broken up...unlike Delight aka Darling aka his current girlfriend. And Bitterbat and Gabe are on good terms since the bat man can now tell who feels romantically towards his sweetie and who are pals.