Most Helpful Girl
I would take her out on a nice date/ make dinner at home with a bottle of wine and make her feel special. You two could just be in a rut and there’s nothing like making sure your lady feels special. Sometimes guys just want to fuck all the time and all of the sensual stuff about sex goes out the window making it feel like a chore for her. If the night doesn’t end in sex after you taking her out and working her up for you then maybe have a talk about it. Make sure not to get upset about it but rather just ask her. Good luck!
Most Helpful Guy
The spark of sexual desire usually wears off through time, so this is a normal process in a long time relationship. Women are more keen to suffer this lack of sexual appetite sooner, but men also experience it overtime.
The emotion, the thrill of a new adventure, a new body to bond with, new experiences in bed to share, is lost. And it becomes routine, and with routine arrives apathy. This is a prominent reason for which men (and women very much alike) seek for romances/adventures outside of the relationship - which of course is cheating.
But it is not that difficult to turn the spark back on. There are several techniques such as the more popular of impersonating other characters, or the more scary "trying new things" in your sexual life.
This new things can only be achieved with communication and hence mutual approval, and reluctancy to comply is a common denominator. But a leap of faith has sometimes to be done: if you haven't tried it, how do you know you don't like it? (or maybe you have tried but did not perform it correctly, or in the right moment?). I'm not telling you which things you can do to spice up your sexual relationship in regard of trying new things: your mutual imagination and sincere communication will set the limit.
Last but not least, don't fuss too much about it. We all go through periods of sexual inapetence, and often it has nothing to do with the relationship itself but with external factors (which can range from job or family problems, to health issues). I'm not saying it is not a warning sign at all, but take it with patience, be observant and respect her space. And in future sexual approaches (which I advice you strategically space in time) be original, funny, different in some way, and make sure you work your way demandingly - just like the they when you were trying to seduce her for the first time.
Good luck :)