Honestly, it doesn't sound like if you want your boyfriend to deliver you consistent peace, that it's going to happen with him. It also doesn't sound like polyamory is what you really want, but you're trying to fit yourself to it because you love him.

Peace may be something that you have to find from something else. Maybe in concert with him, but it doesn't seem like he'll be able to give you the peace.

*based only on what I've read from you, obviously I don't know your actual life beyond what I've read and it's limited info so I could obviously be wrong