Who said flirting was for couples in a honeymoon stage? 

Make an effort to be more flirtatious with your partner, regardless of how long you have been together.  Send them a cute text, give them a compliment, or just be silly together.

Not only does flirting help to maintain intimacy and increase self-esteem of both partners, it also helps to reduce tension and fighting.  Read more about the benefits of flirting in long-term relationships here!