She’s changed, but IDK how much of it’s from me and how much is from just her growing up. We’ve definitely become more mature and she’s more rational and level-headed now. As for how I’ve changed, I’m honestly not sure. Like at all. I’d need to ask. How much of that is from our relationship and how much of that is from other factors I can’t say. I’ve only been in one serious relationship in my life and for a good chunk of it it was long-distance (one of the reasons it ended actually). I do know that relationships can allow people to evolve, become more mature or compassionate or aware. So yeah, I’d say they can expand and alter your personality, but I can’t say I’ve seen anyone go through a drastic shift of their persona from a relationship.
Or are you asking if they alter their personality during the relationship. In that case, I’d give the same answer. A person’s personality can change over the course of a relationship but I’ve never seen an immediate, drastic change in a person the moment they start a relationship, or at least not one that wasn’t just superficial.