ma dud, Twily and Trixy would totally hook up for that sweet chemistry that comes with rivalry between two ambitious people. but it indeed would burnout pretty quickly. now i dunno whom you'd give the roles of Twi's exes, but here's important question - in the early days was there anyone who was trying to date Twi for gain, maybe even manipulate her? like making rumors and feeding them to tabloids and using the commotion to tell Twi that she'd look bad if she would deny them? COUGHBluebloodCOUGH
I don’t think I’d assign certain characters just to be list of names that Twilight’s been with; Trixie was an exception ‘cuz I can see her being buddies with Rarity and teasing Twilight every now and then while Twi would blush and pout on the sidelines with Starlight (who’s totes Trixie’s girlfren let’s be real). BUT in the context of Twilight being chased simply for her status or money, I’m sure it’s happened before: she was very obviously single and rising to fame and they wanted a piece of that, so they tried to romance her. I think it’d happen at least twice before Twilight eventually just swore off relationships for a while and simply just put any idea of a romantic endeavor, brief or serious, out of mind. So she’d be out of the “dating game” for a few years and focus entirely on her work.
As for an example of a bad relationship, hmm… I mean Blueblood would be an obvious choice but if that’s the case I don’t really see him being manipulative so much as it’s him being unbearably shallow and not putting in the effort for their relationship, so it died really fast but unlike the others, it didn’t end so well.