If you don’t get along with your friend’s partner, try to approach at a calm time when you can talk one-on-one. Let your friend know that you miss him/her and ask if the two of you can make plans to hang out again, just the two of you.
If you find yourself getting jealous that your friend isn’t spending enough time with you, try to put yourself in their position and remember the feeling of being in a relationship. Your friend may not even be aware that your feelings are being hurt.
If you simply have a bad feeling about your friend’s partner or dislike them for an unknown reason, give careful thought to if and how you will approach your friend. You may need to take some time and self-reflection to get to the issue at the core of your negative feelings.