Is your partner complaining that you no longer want to have sex or when you do it feels like you're just going through the motions?? Have things turned very mechanical and boring in the bedroom? Would you admit that you often can't wait for it to be over before it even starts? If you answer YES to any of those questions, there are probably some underlying issues at play...
For starters, it's important to understand what your biggest sex organ is...It is NOT your genitals; Rather, it is your BRAIN! The first step in turning this around requires your brain to receive the green light to feel like a sexual being again. Then it is helpful to find ways to help your mind re-engage in desire for your partner (ie: maybe play romantic songs, reminisce about past sensual memories, watch something sexually explicit, read erotica, etc.). It is important to give yourself permission to feel sexy again, in order to re-introduce AROUSAL back into the relationship...Don't be discouraged--with intentional work, this can change!
Second, the other reason that you may have a low libido is because there is unresolved anger and resentment held towards your partner, which is the #1 reason why people tend to stop wanting to have sex in their relationships. Working with a trained sex therapist can help you find your way back to each other again. Just remember, the bedroom is often a window into the entire relationship...there is often more going on than what meets the eye.
Invest in making both yourself and your partner sexually satisfied...because if you don't, there's a very good chance someone else would be more than willing to try to please your partner!!