Time is the best teacher. It grants you with experience and insight. For me, time as taught me to stop living in the past and let go of my regrets. One of the major ones being me pushing everyone away. I don't regret that anymore. There's no point in it anymore.
That's not to say that I hate anyone or that I'm happy they're gone. I'm not on my own island flipping everyone off as they sail away. Not at all. I'm happy they've moved on to new islands and begun to build new lives for themselves.
To be honest, the main reason I felt regret was that I was alone and everyone seemed to have so much going on in their lives. Which is a great thing, but when you have nothing going on in your life, you start get trapped in your own head. You start to compare your life to other people's, which is a really shitty thing to do to yourself.
While I don't feel bad about my failed friendships and relationships, my time feeling shitty about them did teach me some important lessons. I've learned not to be sensitive and to give up on everything at the first sight of trouble.
I used to just sit on my island and feel regret and sadness over my past failures in my life. I would look over at the other islands around me and marvel over what they had built for themselves. Jealousy would fill me while sitting on my empty and lonely island. Now I've learned to build on my island. Maybe it'll attract new people, maybe it won't. As long as what I build is stable and strong, I'm happy.