It's really not difficult to ruin what could have been great sex. If that's your goal, following these twelve suggestions will ensure that, over time, your spouse will become very creative in finding ways to avoid having sex with you.

Of course, I'm writing this article "tongue in cheek" to make a point. But I can assure you that these behaviors will detract from your sexual relationship with your partner. That's because sexual feelings are vulnerable to being affected by so many other factors, such as self-esteem, expectations, criticism, emotional intimacy, and pressure.

So here are the behaviors guaranteed to be "turn offs" to your spouse. In quote marks is the faulty reasoning that gets marriages into trouble. In parentheses (...), I've added a counterweight to the faulty reasoning.

1. Develop a set routine for when you want to have sex-the same time and same place every week.

"That way, you don't have to wonder when you'll have sex-Sunday night at 9:00 p.m. in the bedroom-just like clock work. No use leaving it to chance, right?"

(How boring. Try adding excitement by surprising your mate with something slightly new and different.)

2. Follow exactly the same "plays" and "moves" each time.

"This way you both know what to expect each time. It's just too much work to come up with different things to try, and after the honeymoon period, it's not really necessary, is it?"

(Instead, remember a variation on the old saying that variety is the spice of life... and of sex).

3. Drink a lot first so that you're loosened up.

"If your mate doesn't like the smell or wishes you wouldn't drink so much before sex, it's just too bad. You can't let your spouse tell you what to do, can you?"

(Consistent and excessive intoxication during sex is a big turn-off and could indicate deeper problems.)

4. Only touch your spouse when your goal is to have sex.

"Save your hugs, wet kisses, and holding hands until you're ready to signal that you want sex. That way your partner will associate your touch with sex and know what to expect, get my drift? Cuts down on misunderstandings, doesn't it?"

(Actually, the best sex can be the result of hours or even days of buildup with no obvious sign of sex on the horizon. During this time, any sign of affection - a touch, a hug, some compliments - can be powerful foreplay that builds to ignite passion.)

5. Expect your spouse to deliver the sexual goods because you're married.

"Your mate knows that every 'good' marriage partner owes sex to the other partner as part of his or her 'duties.' After all, isn't this supposed to be one of the benefits of being married?"

(When sex becomes an obligation, it becomes as appealing as paying taxes. Instead, if your goal is to make the experience breathtaking for your partner, you'll never have to invoke guilt or obligation to get sex.)

6. Push for sex even if your spouse seems reluctant and uninterested as long as he or she says "okay."

"If the verbal agreement is there, ignore the behavioral signals that indicate reluctance. If your spouse didn't really want to have sex, he or she should have said so up front, right?"

(Pay close attention to your mate's body language. That can be more revealing of true interest in sex than words alone. You'll damage your relationship if you forge ahead when your partner only agrees just to get it over with.)

7. Skip foreplay and get to the major action immediately.

"It takes too much time to bother with all that extra stuff. Besides, both of you have to go to work in the morning and need your sleep. You can't afford to waste time."

(The truth is, there is often a direct correlation to the amount of foreplay with the quality of the sex. The better the buildup, the better the payoff.)

8. Criticize your spouse's sexual performance.

"After all, you're only trying to motivate your mate to be a better sexual partner. It's not healthy to keep things in, so he or she will just have to listen to your critique."

(You will get more satisfying performance out of your mate by praising what he or she does that you like, rather than the contrary.)

9. Criticize your spouse's physical appearance.

"If your partner has developed a beer belly or gotten flabby, you're doing him or her a favor to say how much that turns you off. It'll motivate your spouse to lose weight and shape up, which will help him or her in the long run."

(The rule is: use positive strokes to motivate your partner. Negative criticism will poison your sex life.)

10. Answer your cell phone during sex.

"You just never know; this call might be important. Anyway, what's the big deal? It's not like you'll never have sex again. You've been having sex for years now, so why should your partner get upset with an occasional interruption?"

(Respect your partner with your undivided attention to get back the same. Minimize all distractions if possible.)

11. Get it over with as fast as possible as long as you're satisfied.

"Don't ask your partner if there's anything you can do for him or her. Just assume that everything's okay unless your mate says something."

(If satisfaction is not mutual, your sex life will suffer. The simple question a couple can ask each other - "How can I please you?" - works wonders.)

12. Jump up immediately and make your get-away afterwards.

"The faster you get finished, the faster you'll be able to get to sleep. There's no time to waste just lying there talking. You can talk tomorrow over breakfast."

(Emotional closeness is the currency of intimacy and you can achieve it by allowing each other to share honest feelings. Pillow talk after sex is one of the best times for this.)

Nancy J. Wasson, Ph.D., is co-author of Keep Your Marriage: What to Do When Your Spouse Says "I don't love you anymore!" This is available at http://www.KeepYourMarriage.com, where you can also sign up for the free weekly Keep Your Marriage Internet Magazine to get ideas and support for improving your marriage.