Yes I have been involved with a sociopath although at first the signs weren't that obvious. Quickly, however, she changed dramatically which really confused me. Whenever we were together I felt like I was walking on eggshells just to keep everything calm! But one false step and boy did she round on me!
Thankfully I saw the light, and her lies and manipulation became apparent. She was hell bent on changing me to her own ideal so I guess I was lucky to escape...and it does feel like I escaped. I could never live up to her ideal and the daily struggle of trying to achieve the impossible would of had a serious detrimental effect on me. An experience to learn from.