Why did my (25M) girlfriend (24F) take me back after cheating?

I’ve been contemplating breaking up with my 7-month girlfriend for months but I hate conflict and seeing her cry (we almost broke up once already but she got upset and talked me out of it). I thought it would be easier if I could get her to break up with me instead so I wouldn’t have to be the bad guy.

After she returned from visiting her family yesterday, I confessed her that I hooked up with a girl from work (fine im a bad person whatever). But instead of dumping me on the spot, she said she could forgive me in time and suggested couples counseling.

I was stunned by this, especially since on one of our first dates she said that infidelity is a dealbreaker for her. Why won’t see leave me?

TLDR: I cheated on my gf and that still isn’t enough to get her to leave me