She cheated and I caught her. I was stupid and in love and thought we could fix things. She set up therapy to try to get me back.
In therapy she let it known that she'd cheated in every relationship she'd been in. Turned out she'd been hiding that she was bi-polar 2 and she'd decided to stop taking her meds because she thought she was cured. She wasn't.
In the few weeks up until the end she'd also used our joint credit card to spend $40k and put me way in debt.
Like I said, I was still stupid and in love, but I eventually wised up and cut things off. She then threatened to take me to court to take all my money, but thankfully I had a good lawyer and her spending on the credit card meant she got nothing and didn't get the house.