<human>: I'm using a throwaway because my main account is very obvious that's it's me. 

My boyfriends name is John. 
We've been dating for about 6 months now, moved pretty quickly with our relationship. Said I love you within the first month, moved in together within 3. The first few months were great and now things are just stagnant. 

Everyday I get this feeling where I should leave and my ex, Eric, texted me telling me he wanted to try things again with me. I've tried breaking things off with John a few times but every time I do he ends up crying and I feel bad and stay. I do love him and I cherish the times we spend together but I can't stop thinking that there's something there with Eric and I. 

My sex life with John has diminished to almost nothing, it's not that it's bad sex but in just bored with it. I feel like everyday were just going through the motions and am unsure if I want to continue. At the same time I don't want to lose him at all, and I especially don't want to break things off if there isn't anything there between Eric and I. 

I can't talk to my best friend about things because she'll just tell me "if you feel this way now you'll feel it later so you just might as well break up" I feel very lost and alone and scared and feel like I have nowhere to turn for advice.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: ex texted me saying he wanted me back and the only reason I can see not going back is because I don't want to ruin my current relationship just in case it doesn't work.