Complaining partner

My partner’s negativity is driving me crazy. I know, these are just my thoughts but I can’t stand to listen to her constant complaining about everything. She complains about the coffee made for her in coffee shops, every meal that is served to her (even the ones I cook for her). I am complaining about her complaining and that is what is driving me crazy, but every time I hear her complain about something I tense up. She is just so rude and I feel bad for the people who are serving her. How can i stop this cycle?