<human>: So, My on and off girlfriend for the past 4-5 years told me last night that the dog her and I had raised passed away while getting spayed. Naturally I wanted to know what had happened and be there to comfort her because this being my first love, I will always love her.

This is where I fuck up. I stay the night, We get intimate. Normally people would be somewhat grateful this happened, But throughout the years it's been extremely toxic. I cannot count on two hands and two feet how many times we've argued and fought. When we are together, My ability to talk to friends or even hang out with them is abolished.

I've dated other girls, Nice ones and some that we just had too many personality difference so Yes, I have tried out the dating field. But I don't like dating, I hate having to re-learn all this shit about someone. My heart wants for the relationship I had to work out, But my Brain knows that it just couldn't happen.

I cannot seem to break this cycle, Could part of it just be due to the fact that I struggle with depression? That the depression is clouding my ability to just say no?
I could have just walked out last night after comforting her and left but I, Me myself chose to stay. I wasn't forced too, I wasn't chained to the walls, And I wasn't with her in a relationship standard. So why did I stay??

Like I said, In my heart I want it to work. But my Intellectual side knows it will not. How can I break this cycle reddit? >:(

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Dog died, Went over to find out what went wrong. Shagged ex gf and stayed the night. Cycle repeating.