Bart had been completely truthful when he'd told Cassie that she was the girl who made him like girls, Carol had been his friend first, and a girl second. Cissie had been something similar. She'd been a girl first and a friend second, but there hadn't really been any romantic feelings in the mix.
Cassie had been a wonder from the time she'd led the team, opening him up to a whole new world.
Was it any wonder that Bart had been so jealous of Kon, for having her attraction, and later, love? And Kon, lucky as he was, managed to have Tim's affection, too, even if he was too oblivious to see it, and Tim too scared to show it.
Bart, however, had a plan, and the reputation of being naïve on his side. He had left a note (typed on the Towers' computer at speed while he was supposed to be doing his homework) for Kon, supposedly from Tim, detailing his affections in a very Tim way. He'd then left a similar one for Cassie, with less detail, and also an apology for the feelings.
He'd ended them with, Nightwing said it would help me to get my feelings on paper, and I suppose since I won't be sending this anyway, I might as well follow through, thus absolving himself of all guilt (in the eyes of everyone else). With Nightwing in the Outsiders, it would be weeks before he was discovered, and by then…
Well, by then his 'friendly offer' of a comforting shoulder to Cassie would be much more, Bart hoped.
Hopefully that whole rebound thing was a cliché. If it wasn't…well, at least Tim and Kon should be happy.