I almost did that with my wife. Soon after we first started dating, she started engaging in care taking activities. We would be at my house watching a movie and she would start doing my laundry. ( I'm not promoting traditional gender roles here, calm down ) I had been in so many transactional relationships, so I felt threatened. We got in a big fight and the positions where basically this:

Me: Nobody asked you to do my laundry, it's not your job. What exactly is going on here? Why are you doing this? What do you want from me? I'm not sure I can give you what you want. You're freaking me out and I wish you would stop.

Her: I just really like you! I was just trying to do nice things for you. I don't want anything from you. Why are you being such a dick?

I left my house in anger and told her I needed some time to think. I thought about it. I recognized she was just a nice person. I realized that's what I really wanted. I also realized I was being a dick. I went back, hat in hand, and apologized. I explained to her that I was simply afraid. I didn't believe that she was being nice to me and it was that simple. I told her that I wanted to be with her because she was a nice person.

I hope you find a genuinely nice person. If you do, you don't have to constantly examine their motives. You'll trust them because you know they are trying to do what is right.