already isolating

i have been talking to my girlfriend since august and we have been "official" for a month and a half now. i like her a lot. she is extremely beautiful and kind. i feel like she's out of my league and have from the beginning. before her, i was single for 2 years. i also don't have many friends. she knows about my mental illness and i try to tell her how i'm feeling overall each day but sometimes i just don't want to explain why i'm upset or having a bad day. i have already started to isolate myself from her. lately, i don't text her with as much enthusiasm as i once did. to her, it really seems that i don't care. and i think i do. but i don't feel i can show it. idk. we broke up last week because of "communication problems" even though i was doing my best. but i take everything personally and i get very defensive. she says i'm mean. i hate that. i feel like a terrible person. she deserves to be happy and i told her that. but she asked if we could try and i told her that i really didn't think i could give her any better than what i already was. and she said that it was okay. she tries really hard to talk to me normally. but i feel so disconnected. i don't feel like we are close at all. we have only kissed because we are both shy. she has also started to annoy me. i wish that didn't happen. i don't know why it does or why i act this way. i'm sorry this is so long.
also i have bpd, bd, gad
does anyone know why we isolate? any advice? experiences? tips?

I personally isolate because I need to rest. I can't handle 24/7 stimulation from outside sources, including relationships.

The truth is that MANY people....at the start of a relationship....expect to be attached at the hip to their new partner. And well, if your needs aren't compatible with their wants/needs....then they think that you don't like them, even if this couldn't be further than the truth.

Can you try talking to her and telling her that you need time to yourself? A good person will understand its not about them. If someone takes offense to it, kick them to the curb as they won't ever be able to understand the complexities of someone with MI struggles.

i isolate for that reason too, but i mean emotionally isolate like distance yourself from one person more than others. we have talked about it, i just don't see an end to my behavior. she is hopeful though. which makes me feel worse. we were very emotionally close very quick in the first month but now i feel shut off completely. thank you very much for the response.