Can you recommend me novels about A loves and engaged/in relationship with B, but B loves C, and C loves A,the endgame would be A and C ,better if the story about transmigration or reincarnation where A = the Villain/antagonist or mob character or canon fodder in original who transmigrated or reincarnated B and C = the ogProtagonist
Do I understand it correctly that you want BL or perhaps yuri novels? For BL you can try This World Has Gone Crazy Reborn As The Villain President’s Lover - has something like that. MC transmigrates into book. In original book A (=MC) loves B, B loves C, B starts abusive relationship with A ends up destroying A. After transmigration it becomes A loves D, B loves C, but then B switches to liking A and ends up in an abusive relationship with C. And A ends up with D.