What causes someone to become reclusive in a serious relationship?

It seems everytime I get involved in a serious relationship I dont talk to anyone but my significant other. However, i have recently realized i tend to get seriously involved with controlling and/or demanding women. A lot of times in these relationships i feel like its too much work to try and have my own life. For instance my current girlfriend likes to ask about every tiny detail suspiciously almost as if ill slip up. She acts like a damn detective or something.