Would you be upset if someone did a background check as well as credit w/o your knowledge?

Before i moved to Florida from Michigan to be with my boyfriend, whom is now my fiance, his stepmom did a background check on me without my knowledge or his consent. I did have shoplifting on there before i was even legal. The fact of the matter is that i was with my cousin whom shoplifted but i was with her and covered for her in the dressing room. She brought this to my fiances attention, not knowing that i had already told him when we were only friends. We met online and i know that is very scary to some people but my family would never go behind my back to do such a thing. In my eyes, they are telling him that they do not trust his own intuition. He is 32 yrs old and not a kid. When i was first told about this by my bf then i was very upset. She had stolen my luggage tag with my information on it when i was at a concert with her stepson. I was mostly mad about her stealing from me when she did exactly what she was judging me for. Since then, we've had problems with her.