The intrusion of "sex on demand" challenges the intimacy of your relationship. Additionally, when woman and a man are under stress (and trying to conceive for long period of time is stressful), there is a good chance that their sex drive is going to be negatively affected. Consequently, if you aren't interested in sex, that obviously limits the ability to conceive.
Is it possible to bring the passion back? Absolutely! You have been able to make time to enjoy sex before and you can do it again.
Following are few suggestions that could come handy when taking the time to rekindle the fire.Schedule a weekly date. Spend time with your partner, go out to a dinner, share a bath, go for afternoon walk. Focus on you two only. Redirect your attention to sex. Discover what arouses you and your partner. Discover your bodies again and renew your sensuality. Perhaps just the candles and some music will make the place right, perhaps you could include some (erotic) massage, or maybe even lap dance. Make sure to have time for your selves, no interruptions. Just the two of you.
When two people spend time together, when they really focus on each other, this truly does bring back the passion, and arouses sexual desire. There are numerous studies done on female and male libido, and most of them include the conclusion that every kind of woman, pre-menopausal, pregnant, peri-menopausal, menopausal, or post-menopausal has a low sex drive. The reason behind is low testosterone levels (male sexual hormone), which is the main reason women often have problems when arousing sexual desires in a long period of trying to conceive.