I think the point is, though, that you may not always consciously know that that is "the only truth". When I told people in the past I didn't see myself wanting to get married ever, that was the truth at the time. I honestly meant it. Now I can see myself marrying my current partner, and that is also the truth. I don't think it's about being unfair or dishonest, it's just about people changing over time. If Oliver did decide to get married in the future, for instance, I wouldn't assume that automatically means he was secretly just lying to Carrie about his thoughts on marriage their entire relationship. That might happen in some situations, but it is also possible to genuinely want to be with someone but not want to get married, and then meet someone who you do want to marry, so you change your mind about marriage.