Communicate clearly with your partner
As mentioned before, anxiety is about worrying about the unknown. Your partner is worried about things he/she has no control over, and that includes your actions. You need to be as clear and transparent with them. In other relationships, you might try playing hard to get, or having an attitude for no reason, but not in this one. Tell your partner if you’re annoyed, sad or mad. Try to pick up his/her calls when you can. Reply to a text as fast as possible. Things that might seem mundane to you won’t be that way with them. The least move on your part and they start overthinking and start worrying.