confusion hormones and insanity

hi, i lived with my girlfriend (fiance for last 10 months) for 6.5 years. we had a good relationship. we got engaged and were making plans for the future. we got engaged in sept. 2016. i was working 2 jobs and going to school part time. in spring 2017 i quit both jobs and started driving uber so i could go to school full time. at her urging i bought a brand new car in april. and money got a little tight. not too bad but tight. around this same time she went off birth control so we could have a child soon. may and june were great. she was always "in the mood". first week of july she told me she was moving out. stating that she had been unhappy for years (not true as she always told me how happy she was). after a week of her sleeping on the couch. i went to work one morning and told her i loved her as i left, she gave me a dirty look. later that day while i was out, she moved out taking our 3 cats with her. she stayed at her parents. i tried calling and texting her but she ignored and didn't respond. within a month she has a new dude and is in a full blown relationship.i was still in our apartment. she came by to get some stuff with her new dude on the one year anniversary of our engagement (of all the days) 2 months after that they moved across the country together. she also still has my engagement ring. what kind of insanity is this. i know she was true and loyal until this. but who jumps from an almost 7 year relationship/engagement into a new one that fast. (and what does that say about the new dude who while helping her get some stuff from our place stole some stuff from me(i was not there).and why wont she return the ring? i am very hurt and confused.

I'm sorry to say but she wasn't loyal at all. Things moved too fast, so it's more than likely she cheated on you. Bare minimum on an emotional level.

Be glad she's gone tbh. You don't need that cancer in your life. Let her become someone else's problem

Hi, I'm sorry you're experiencing this, it must be extremely hurtful.

I'm afraid I agree with rustysuit. I think she moved on while in the relationship with you, possibly in the months before. Agree it may not have been physical. It was likely the reason for her leaving. She then rationalised around it with her new perspective that she'd not been happy before.

Yes you are better off without her, her actions speak volumes and show her to lack integrity. The coming off birth control to have a child when she was likely pulling away from you is odd, but maybe she didn't actually come off it.