He probably meant that new persons are more interesting than ones who were always around you, at least for most people.
It's the pleasure of something new, a well known thing.
Keep yourself together man, you're living in the USA after all. There are ways to change this. Just grab a gun and go for it!
On the other hand, you would obviously hurt your sister emotionally. Nah nevermind, bad idea.
I personally became very demanding when it comes to a girlfriend because of having played too many visual novels.
I don't regret anything though.