Hello, I am new to this subreddit! I don't know how to start this but I'm just gonna provide some context.

I (M22) have been dating my gf (F23) for over a year now. I really think she has BPD although she hasn't seen anyone nor am I a professional. We met online last year and she was far away. We really clicked from the start and talked for months before I went to see her. It felt really really good. But there was difficulty from my parents with coronavirus and so on, so seeing her often wasn't an option. The long distance bit is important in an example I'll get to.

I love her a ton, the highs are really high in the relationship and the lows get very low. And it usually hinges on her mood. If she's happy the relationship is good, if she isn't it's rough. Although it's not just her, it's me, because when she takes a turn for the worse, her strong emotions against me really end up triggering me and I become frustrated. 

For example... This past weekend we spent a decent amount of time together. Saturday I woke up late and we called and talked from about 12PM to 4/5 PM. I told her I wanted to go do some things around the house because I had chores to do, so I ended up eating, yada yada, but not getting much done. I then started to text her again at 9 or 10 PM and we video chatted and watched a movie. I explained that I had to get up early the next morning so I could do the rest of my chores. 
So Sunday comes and we wake up still on the phone from the night before and I talk to her from like 9 to 10 AM. I then get up and do all my work straight until about 4 PM. I finally checked my phone again. She messaged me a while ago so I messaged back. I eat and do my thing and hop on some video games with my pal. I last checked my phone at like 7 and still no response from her. So I assume she's just off on her own. So I play with my friend until about 10:30 or so and I get off and check my phone see she's been asking about watching a movie again, like a few hours ago ~7:30 and 9. I instantly feel bad because I miss her and she's been trying to reach out. So I end up finally reaching her and she's absolutely devastated and starts balling. I apologize for a bit because I can empathize with her. But then she goes sicko mode on me and says stuff like " I didn't know spending time with me was such a bad thing, fu*k man" and I explained how I had been gaming with my friend and she says stuff about how I always spend time with him.
 Which contextually, I talk to her most every night for at least an hour, not to mention other times through the day. And since we are long distance I do go to see my friend on weekends because I want to be social. She takes offense to this and acts like I'd rather be with him, vs she doesn't understand that we are long distance and I'd love to be with her but it's physically just not an option. So anytime I give to other people she really has a hard time dealing with and gets upset or holds it against me. 

But back to the story, she says a few more things about how she wants to be in a relationship where she's prioritized and then she says stuff about how she's pretty and why would I treat her like this. Meanwhile I get really upset and honestly angry because I feel like I have to defend myself in her eyes. And while she's spiraling out the only two methods I have of communicating with her are either to cry and get her attention or to get upset and get her attention. Otherwise she'll spiral and keep thinking about the ways I could hurt her and she sobs and sobs. So I felt and feel pretty awful cause I blew up and didn't say anything too terrible but I hate that. I am upset I couldn't control myself.  

I don't feel like I did anything wrong? I was just playing games with my friend. She sees it as, "you forgot about me and don't care about me" (her words).  There's been other things that have happened before that follow these same lines many times and for a while. 

So after reading about BPD and some of people's experiences, I made the association that maybe she has it. 

She's pretty dead set on thinking she has Pure O, OCD (not diagnosed), And looks for therapy in that specific realm but I think she should get diagnosed with whatever and then work on it. 

I guess I'm asking if anyone can relate and if so, how do I approach her when this happens?? I feel as though can't get through to her unless I cry or get upset, both of which prove the severity of the situation to her (shes said this herself). I really don't want those to be my only options though. 

Thanks for reading this far. I can provide more examples if anyone is curious.

Tl;dr : I think my girlfriend may have BPD and Im looking for ways to try to approach her when she's spiraling out, because I normally can't get to her.