You might excite each other in the beginning, and think you've found what you've been looking for -- a lover whose drives match your own, who has ambitions and goals to pursue, who has a healthy interest in and appreciation of sex play. You might have athletics in common, or playing board games, and you might enjoy a certain amount of healthy competition and ribbing each other. But that competitive spirit could just grow and grow, and overshadow everything that's good and easy between you as a couple.
After some time, you both start to notice that some of the fun has gone out of your connection. Instead of having a great time playing together, you're challenging each other, acting like opposing teams instead of united teammates. Your sex life could reflect this dynamic as well; instead of caring for you and your needs, your partner starts just pursuing their own desires, acting out their own fantasies, without even checking to make sure it's okay with you. What kind of relationship is that? Not one that lasts long-term, not unless you can both find a way to tone down the challenging, competitive spirit and check in with your lover from time to time. You might need to remind them to ask you, How are you feeling? Is there anything I can do for you, to make you feel better?