Last night while I was on the phone with my girlfriend (M), she was talking about how frustrating her roommate (H) was being (boy drama), they had an altercation over it and were spacing out a bit. M proceeded to go and check on H a while later, and came back more upset, saying H had said she wanted to be alone and didn't want to speak to her. M then started saying how she just wants to be around H all the time, how her presence makes her feel better and how she just wants to hang out with her. M continued saying she wasn't sure if she was beginning to fp H, and that she doesn't WANT to have an fp. She says I shouldn't worry, but last time she had an fp, she forgot I existed and it ended in us taking a long break. 

I want to be supportive and not seem like a dick, so I plan to have a conversation with her. I'm not very good at communicating my thoughts, so I made some bullet points of what I wanted to ask:

• Extent of obsession
• Why is this happening in the first place 
(The attention given, or lack of?)
(Am I meeting your emotional needs?)
• How this will affect you 
• How this will affect us 
• Understand your thought process and the steps you'll take to prevent furthering the obsession 
• What solutions can we find 

I don't mean to make this about me and stress how distraught this situation can potentially be, especially since I know she's spiraling and hurting, but the ordeal is upsetting. What can I do to support her? How should I go about this? I trust her and her (emotionally) cheating has never crossed my mind.

Am I just overly wary or jealous? How can I stop the furthering of this fp (H is very dismissive of M, and I feel as though H becoming her fp will make her spiral out of control)? I suppose I just need input in general and I'm not sure how to go about any of it. I try hard to understand her bpd, but I can't help but get upset over some things