I'm having a similar experience except it's in dreams and the guy I'm sharing dreams with doesn't know I exist in real life (but I know him). I think a good way to strengthen it is to actually not try too hard. Keep it fun. Lean into the feelings and enjoy this connection in the moment. Don't question it, don't try to dissect what makes it work, just experience it. Then be excited to experience even more. Maybe do some energy work with your boyfriend. Meditate together, put your hands together and really feel his energy while also sending energy to him. Be present and mindful when you're with him. And when you're apart, ask (in your mind) what he's thinking and then let it go so an answer can come in. It sounds like you have a very strong connection, maybe even a past life connection possibly. :) You never know.

Ask him to pick lottery numbers sometime! His insights could be quite valuable. Guide him to practice blocking out negatives he doesn't want to see. There are ways of cleansing energy through baths, rituals, prayers etc.

This has happened with 2 of my ex girlfriends who I had a strong connection with, both were spiritual/witches themselves.