'Can I steal something from my ex for a keepsake?'

Is it okay to steal something from an ex-girlfriend as a keepsake? I want something to remember her by.
Stealing is a crime. Why not behave like an adult and simply ask for something instead?

I wanted to marry a traditional woman, so I spoke to my family members and they asked around and found someone they thought was perfect for me. Things were great during our honeymoon, although I kept spotting my wife taking pills every morning and night. When I asked her what they were for, she said they were just vitamins, so I let it be. One morning, she realised her pills were over and began to get increasingly agitated. By that evening, she was in a rage, throwing things around the hotel room and screaming. I called my parents and told them what had happened. They called my in-laws and eventually found that the pills were mood suppressants because my wife had a personality disorder. I was shocked and felt cheated, because this was never mentioned to me during our courting period. I asked my in-laws to take her home, but they refused, saying I was her husband and she was now my responsibility. How do I get out of this predicament? I feel as if my life is over.
If your wife is ill, all she needs is treatment. If you love her, and have decided to marry her, the idea of being together through sickness and health is pretty much what you have signed up for. While I agree that your in-laws ought to have come clean, this is unfortunately how some people choose to function. Through this entire incident, no one has bothered to ask your wife how she feels being tossed around like this, when it is her opinion that should be a priority, considering she's the one who is ill. Speak to her first, understand where she's coming from, and visit a doctor with her before you make any rash decisions. You owe her that much.