You're nice, Libra. Probably too nice. You just hate the idea of hurting anyone's feelings, so you go out of your way not to, even when it means lying through your teeth.
Well, to be fair, in the moment when you said those things, you actually believed them, so technically it wasn't lying, even if you came to your senses five minutes later. But by then it was too late, and you couldn't bear to make them cry, so you kept mum and went along even though deep inside you, something was screaming. Days, or weeks, or months or years later, the truth finally came out, and generally not in a pleasant way. And thus ended another relationship. Oh, by the way, that's not even mentioning the ones that got away because you couldn't decide yea or nay on them.You are what you are, and there's little point in telling you to just make up your mind; that's next to impossible for you. But you can get over this silly need to protect others from your truth (what do you think will happen to them, anyway, if you speak honestly?). Put your needs before theirs, for once, and you'll be surprised by the improvement in your relationships.