Although the comments keep saying that it doesn't work like that the thing is that i've noticed in my life that when someone spends a lot of time with me they begin to speak less fluently and stutter a little bit, and it is unconscious because they also stuttered when speaking with other people other than me. But I don't think it is permanent, it is like some kind of social mechanism if i had to guess. It happened to my little brothered when we spent a lot of time together and with some friends, specially with the one i lived for almost a year.