Ask any couple in a long-term relationship about their sex life and you're bound to hear something along the lines of, "It's not as hot as it used to be, but I guess it's still pretty good."

Waning sexual passion over time is the norm for every couple, says Pat Love, Ph.D., the author of "Hot Monogamy" and "The Truth About Love". But the change in desire is usually different for each person.

Desire discrepancy — when one partner has a greater sex drive than the other — is what emerges about 18 months into a relationship, when you're out of the infatuation stage, claims Love. This imbalance is why sex often goes from hot to cold in committed relationships.

Luckily, differences in sexual desire can be resolved and you can reenergize your sexual connection. The key is to appreciate and respond to "your partner's language of love," asserts Love, because "the way to get what you want is to give what your partner desires."

Communicate Your Desire

But first, you have to be able to talk about sex, and that's where couples often hit a brick wall, says Susan Townsend, director of the Relationship Enrichment center in Towson, Md.

Many of us have a hard time communicating about this difficult topic, so we say nothing or we say it in a negative way that closes off communication.

Townsend offers this example: Perhaps what you truly desire is more kissing during foreplay, so you say, "You know, you never really kiss me enough." That is not a desire; it's a criticism. The wording of desire might be, "I've been thinking. Instead of jumping into sex it would be really nice to spend more time kissing first."

The technique is to identify the desire behind every criticism and express it using the language of "rather than" and "instead of," says Townsend, who leads Hot Monogamy sexual workshops. "You wouldn't believe the leap in sexual communication when people start saying, 'Instead of doing..., I'd rather you do...'" she reports.

After you state your sexual desire in a positive way, your partner validates what you've said by repeating it — without editing. You make corrections until he/she gets it right. Then you thank your partner for hearing you and ask if she/he is willing to change to meet your desire. Your partner may reply with a "yes" or "no" or agree if certain conditions are met.

Using this communication technique, also known as "mirroring," may not always result in what you want, but you'll have a much better chance of getting your desires met if you learn to transform your criticisms into requests and pay attention to receiving from, and giving to, your partner.

Furthermore, this style of sharing creates a deeper level of emotional intimacy, which often leads to greater sexual passion.