22yo here. I am very socially active, but that doesn't change anything. Borderline Personality Disorder isn't really something you can get over with by being more sociable, as a matter of fact it sometimes makes it worse, because it makes you feel like you're in a limbo, not really sure about who or what you are or if you really matter to any of those people. With time I found out that hanging with fewer but way more close friends works better for me. Now regarding emotional attachment to someone (often called FP, Favorite Person), that is very hard to control and often just happens. It is pretty fucked up, but at least I'm somewhat getting used to it and slowly starting to understand it.