SUBREDDIT: r/relationships
TITLE: Advice please- I called out his best friend's name.
POST: I (f, 24) have been seriously dating my boyfriend (m, 25- Let's say his name is John) for about 4 months. We have a really great relationship and care about one another quite a bit and have never argued, until now. 

John's best friend "Tony" always hangs out with us. It's not a problem- we have all been friends for a long time. However, recently I started having dreams of Tony. Not always sexual but some have been and now I am concerned as a few nights ago I called out his name in my sleep (no I do not remember the dream). 

I actually have no desire to date, or even fuck Tony. Yet John and I have been getting into silly arguments recently where he accuses me of wanting him, or if I do something different in bed he gets upset and asks if I was thinking of Tony again. 

Please help. I have told John time and time again it is not like that, but I do not have a way to reassure him other than just saying I don't- which isn't working.
TL;DR: 
I had a dream of my boyfriend's best friend and called out his name in my sleep. Simply saying it was nothing is not working, what else can I do?