I'm pretty cat crazy myself and have to remember to tone it down.
Sounds like you've gotten some great advice! Something I've noticed that works is if I can't get Max off the brain but need to for OHs sake, sometimes it helps to watch for something special Max only does for or in response to OH and point it out. Then i get to talk about Max but its also about something special only OH adds to the mix. Kind of like pointing out safari glue?
For example, if OH comes near Max's leather strip (favorite toy), Max sits by it.... Really tall... And gives OH the Puss in Boots look. If I pick up the leather to play, Max won't. He wants to play with OH, and OH to see him sitting like a big boy. I pointed this out to OH and it was so cute to watch. Max was delighted to get the attention and OH loved that his boy wanted guy time (& snubbed me!).
Litle bonding moments like that have been my favorite.
Kitty kamping has also been great. If your BF likes camping.... Give it a try.
kitty Kamping gives OH his own experiences with Max to get excited about and share with me.
Good luck!
it's hard finding balance but at least you are trying. That itself shows you care!