I've been dating this girl for about half a year and like everyday something different happens.

Like for example 

She was jokingly texting about another guy in a sexual way and I told her I didn't like that, she felt really bad and started giving me one word answers.

I  messaged her and reassured her that it wasn't that bad just try and not to do it again. 

Still just "ok" "whatever" "lol?" "k" 

I've read some things about BPD and I understand this is obviously a low and I just text them. 

"I'm here if you want to talk, I'm not mad at you or anything."

They'll usually just say "Goodnight." 

They'll actually do this multiple times and I feel like they want me to keep talking to them so I'll keep messaging them but they'll only give 1 word answers. I tell them I love them a lot, I try to make jokes but they only give me 1 word answers.

So here's the question. Should I keep messaging them? Would that be the thing they want, or do they really just want me to leave them alone.

I was also with my friend who is a guy, and brought her along and he showed me a picture of another girl and asked if I think she's hot.

I replied to him by just saying, "Yeah she's good looking."

My girlfriend didn't say much until later when we got home and started calling me a hypocrite because I got jealous about the sexual jokes she made.

I replied with, "Well it was an awkward situation, I'm not just gonna say the girl he likes is ugly when she's not." She did not like this and started giving me 1 word answers again.

When she does this I talk to her a lot and she just takes like a minute to reply to my questions and other compliments. 

Sorry this is all like out of place and there's definitely a bunch of typos but to end it. I just want to ask AM I doing good in supporting my gf with bpd? How can I improve, and what shouldn't I ever do.