Hi Monika, remember that cats are creatures of habit, and changes in the environment and routines will stress them; maybe your cat feels displaced. Sharing their human with another human might not be ideal for them and they can find ways of getting your attention. You are not providing information regarding whether your cat will normally sleep in your bed, but we think if you try to get your boyfriend to bond and win your cat’s trust, that might help. Also, make sure you do not change your behavior towards your cat whenever he is staging over. Good luck!
Why Do Cats Meow at Night? – https://www.catster.com/cat-behavior/why-do-cats-meow-at-night/
How to Bond With Your Cat – https://www.catster.com/cat-behavior/how-to-bond-with-your-cat/

Hi Valerie, many cats do the same when given the choice. It is not ideal, but it is a common behavior in outdoor cats.