The first online affair, I was not diagnosed with anything and had no idea anything was wrong with me. So no medicine or doctors or a diagnosis to help me out, I was just out there. Home life was bad, neglected, ignored, put down...I had anxiety through the roof from my XH. The online part was me in a bubble, where life was an illusion of 'happy'. My ability to make rational decisions was gone. It was months before I was diagnosed and only then because I had major breakdown.

The second time I had been physically abandoned, XH found a job in another state completely, in addition to the other stuff that was ongoing. That abandonment was on purpose after being me being diagnosed 4 years earlier with bipolar and it not being completely under control. He could not watch me in my depressed episodes without becoming extraordinarily angry and frustrated with me. I was not doing 'enough' to get healthy or 'fix' myself, in his opinion...despite him not reading the copious amounts of books and pamphlets gathered in the house regarding my issues. BTW he did the same thing regarding my hearing loss and need for a hearing aid. he sabotaged every conversation and then got angry when I misunderstood him.

All of these problems in my household ended up causing me to finally ask for a divorce once my mood issues were under control and I could make rational decisions. We had tried marriage counseling 5 times by that point. It was never going to work because his mindset was concreted in the idea that I had always chosen everything that happened, including sitting on the couch and falling asleep in midconversation ( a med side effect ).

I am going to say, I never searched out affairs, I wasn't in any positions to be finding affair partners. I made friends that it became stronger in the emotional attachments. If I had not vulnerable in the first place, and been treated correctly with medicine for my bipolar illness, those things probably would not have happened.

Everyone is different, their symptoms, reactions to meds is different, their mindset and strength is different. I never thought in the 20 years prior to my illness that I would ever have done anything like what happened to me.

Hopefully, your gf, with proper knowledge, treatment and loving guidance and support from you will never have to worry about cheating. It's not a foregone conclusion...In my case I have never been on spending sprees or gambling ventures where I lost tons of money. So not everything on the list is a symptom that everyone is going to face when they have bipolar disorder.
I hope this helps explain a little better