From the first moment you lay eyes on her, you know. Maybe not that she’s “the one,” but definitely that you want her in that “can’t wait to have you in my arms, can already imagine kissing you, boy is it going to be good I can already tell" kind of way.

And should you be so lucky as to actually get together, it’s amazing. I mean, really amazing. Movie scene, swelling music, I-think-I-just-saw-a-glimpse-of-heaven amazing.

And then you start dating. It’s great for a while, even better than it was at the very beginning. There’s something great about being a couple, something hot about the security and about knowing how to turn one another on. And then you move in together, maybe even get married, and slowly, so slowly that perhaps you don’t even notice at first, things begin to change.

She’s not desperate for you, clawing at your clothes the minute you get home. He doesn’t wake you in the middle of the night because he can’t sleep. Things are good in every other part of your marriage. And you do have sex … occasionally. And it’s good sex, OK sex anyway. But things are different, cooled off, and, well, the chill is starting to get old.

What happened? You still love her. You still find her attractive. He still has that cute little dimple. You still surprise him with his favorite dinner. You’re the same, but the sex isn’t. Is she not really the one for you? Did you marry the wrong guy? Is life as you once knew it over?

Not necessarily.

When you first meet someone, you have the benefit of enjoying NRE, new relationship energy — that high you get from thinking about the “what if” and from reliving each new moment of the excitement that has just walked into your life. But you can’t keep that up forever.

Things change. But that doesn’t have to be a bad thing. The key is to be realistic with yourself and honest with your partner. The fireworks may be behind you — but that’s no reason that the embers can’t keep burning.

1. Talk to your partner. It’s so obvious, but many of us forget to do it. If you’re feeling neglected, tell him. If you want something different, tell her. Suffering in silence will only make things worse. It’s not always easy to do, but it’s always worth it. If you really love someone, a relationship shouldn’t feel like a prison sentence. If it does, it’s time for a serious conversation.

2. Take personal stock. If you’re expecting things to always be the way they were when you first met, you are likely being unrealistic. Sure, some people say they are as hot for each other now as the day they met, but for most of us, things change. Accepting that — instead of fighting it — can go a long way for your mental health. Don’t think of it as things being better or worse. Just think of it as being different.

3. Be proactive. Instead of grumbling about your partner not wanting to have sex or feeling upset that you aren’t hungry for your partner they way you used to be, do something about it. Plan a romantic date. Leave him romantic notes. Act as if you are trying to win her and not that you already have her. Taking someone for granted is a surefire route to failure. It may seem simple, but a little thoughtful effort can go a long, long way.

4. Look in the mirror. If things aren’t the way you want them, consider who you’ve become. You want more from her, but how available are you? You want him to still desire you, but have you completely lost the person you once were? You want to be “that couple” that everyone envies, but are you putting in the time?

5. Quit comparing. Don’t compare now to when you first met and don’t compare your relationship to that of other couples. The only thing that matters is that you and your lover feel happy and fulfilled. It doesn’t matter if that looks different than it used to, or if it looks different than other people’s marriages. This is your marriage, not theirs. Besides, who knows what other people’s relationships REALLY look like behind closed doors? You have to be careful what you wish for…

Good relationships are about being conscious of ourselves and our partners. Sleepwalking through life is the worst thing you can do to a relationship. We all age. We all change. And hopefully, we all grow. But we owe it to ourselves, our spouses, and our relationships to not completely lose sight of the people we were when the relationship began.

Jenny Block is a freelance writer based in Dallas, Texas. She is the author of "Open: Love, Sex, and Life in an Open Marriage." Her work appears in "One Big Happy Family" edited by Rebecca Walker and "It’s a Girl: Women Writers on Raising Daughters" edited by Andrea Buchanan. Visit her Web site at www.jennyonthepage.com.