It may seem innocent: a lunch meeting here, a friendly gift there; but it can easily grow to cross the line. If you are engaging in a relationship with someone of the opposite sex while you are already married or have a significant other, you might want to check your motives.

Some might say it is not an affair until your have sex with the person. Others may be more liberal than that and say that it depends on what the significant other is OK with. After all, in this day and age many people are having open relationships where another person can go as far as sleeping with their spouse or having threesomes. So, with so much grey area, how do you know when you are cheating?

Here is a guideline for people who want to know if they are cheating or just having a friendly relationship:

1. If you're kissing your "friend" you might be cheating. Kissing is a very intimate act, and I'm not talking about a peck on the cheek or even a peck on the lips, I'm talking about full on lip locks. If you are making out with your "friend" you might definitely want to think about the nature of your relationship. Making out is not something that friends do. Of course these rules are not hard and fast. If your significant other says it is OK for you to be doing this, then you may not be cheating.

2. If you are having sex with your "friend" then you might be cheating. Sex is another intimate act that typically only two people in an intimate relationship share. It is not something that is engaged in liberally with just anybody. So, if you find yourself having sex with someone other than your significant other, that is called an affair. This is also open to interpretation. There are some couples who have open relationships or find it appealing for their spouse to engage in sexual acts with other people. In this case, you might not be having an affair.

3. If you are lying about your activities with your "friend" you might be cheating. Unless you are planning a surprise birthday party for your signifiant other with your "friend", there should be no reason for you to lie about your engagements with your him/her. A relationship is built on honesty and trust. When you start lying about where you are going and what you are doing with your so-called friend, that brings into question what your intentions with him/her really are. Why are you lying? What do you have to hide? If your encounters with your friend are truly innoncent, you should feel comfortable sharing them with your significant other.

4. If you are jealous when your "friend" has another "friend" or gets into a relationship, you might be cheating. If your friend is truly a friend, you should be happy for him/her to have a relationship, someone to make him/her as happy as your significant other makes you. If you are jealous that he/she has his own relationship now, you might have been cheating all this time.

5. If you feel guilty about your relationship with your "friend" you might be cheating. Some people feel inappopriate guilt, so you might be cheating, but you might not. One way to know for sure is to ask yourself, "what do I feel guilty about?" Is it that I'm spending more time with my friend than my own spouse? Is it because when my "friend" touches me I feel butterflies inside? Is it because I tell my "friend" things I don't share with my spouse? Depending on what it is and how serious it is, you may or may not be cheating. Most importantly, if you can tell your spouse what you are doing, and (s)he is OK with it, you are not cheating.

So, there you have it. A comprehensive go-to checklist to know whether or not your relationship is an affair. Be careful out there, and remember if your significant other is jealous you might be cheating!