I don't personally know a lot about a straight DBT approach. My T has previously trained in DBT, but what I've learned from DBT has been integrated with other approaches. I do think that some of the skills are likely to be helpful for all sorts of things, including the isolation you're experiencing.

Mostly I just wanted to say you're definately not alone in how you feel. My therapist knows me well enough to know how exactly much I struggle and how disfunctional my thoughts are, even if I appear completely confident, happy, etc on the outside. Just like you, I also only make acquaintances (very easily), but that's about as far as it goes. For me, I think I learned to shut away all of the bad stuff as a child. I never told anyone about the severe depression and anxiety, but eventually learned to hide it from my family (when I realised no one could help me and I had to get through it on my own anyway). There's something that comes along with that I think. I learned to be very emotionally distant from my family and not need anyone—sort of. I know I appear like I'm fine and happy as I go about my life, but along with shutting away all of the bad stuff comes an emotional distance from other people, I find. Almost as if people can sense that I don't need anyone (except of course I do).

I just wanted to say good luck to you and you're definitely not alone. Once someone who served me coffee a few times a week asked me "Why are you always so happy?" Other people matter to me a lot and really the only thing I like about myself is how much I care about other people. Yet, no friends...

It's not easy! That's for sure.