How do you know if your spouse is acting out or has a more serious condition? Major personality shifts aren't something most are prepared for. What makes things tough is that we think we have our soul mate, a person we know and trust with whom we can spend our lives and not have to worry. We love the predictable nature and the security of a spouse we can count on—possibly the only person we can count on. We think we know who they are and are confident in our knowledge and assume that they would never do anything to hurt us.

There may, however, be warning signs. At first, you may look at each single event or incident as an exception, explained away as an irrational moment caused by stress, an argument, friends who pressured him or her into acting in an uncharacteristic manner. It could be coming in late a few times, drinking too much, excessive spending, a change in dress or friendships, finding evidence of time spent online in a singles chat room. You feel a little scared, surprised and may mention it to your spouse who has a logical explanation or denies it all together.

If the bad behavior shows signs of becoming a pattern, typically most of us would begin to worry about a possible affair. Sometimes it is that simple, very painful, but not unusual in our world. As a marriage counselor with training in addictions, compulsive behaviors and mental health issues, I have learned that there are more serious problems that sometimes arise but are unrecognized until they undermine what once was a secure marriage. I’ve also heard many stories where one party believed it was a secure marriage only to discover after years of deceit that it never was what he or she thought it was.

Here are a few of the possible reasons for that type of dramatic change in someone you love. All require serious intervention and most likely professional help:

Bi-polar disorder is a form of mental illness that can appear at any time in a person’s life and/or worsen to a degree that it becomes extreme and more noticeable. It may show itself as severe depression and/or sudden periods of dramatic mood or behavior change often called mania, such as euphoria, high-energy, riveting interest in something new—an activity (spending, running, talking on the phone, an invention, a belief or a cause)—with an inability to sleep in their previously normal pattern. This can include use of drugs or alcohol to self-medicate and regulate mood, usually unsuccessfully. Bi-polar disorder often runs in families.

Addiction rarely appears in only one form. Gamblers may drink and have an addition to both activities. People who have affairs may also be sexually compulsive in other ways and may also drink excessively. The most common addiction is alcoholism, which is chronic and progressive and lasts a lifetime unless abstinence puts it in remission. I have known couples where their relationship began with a spouse as a non-drinker or who cut back their heavy drinking in the beginning only to return to an addictive pattern when the relationship was more established. What a shock for an unknowing spouse. You may have read about Nicole Kidman and Keith Urban when his relapse resulted in admission to a treatment center after only four months of marriage.

Personality disorders are more subtle and may be more complicated. Symptoms such as rage may be triggered on a regular basis by certain situations or people. Individuals may become extremely critical of their partner, verbally abusive and unreasonable and then apologize profusely promising never to do it again. This may be present in physically abusive partners as well, but not necessarily. The difference is often hard to discern but a personality disorder tends to be permanent and yet helped somewhat with treatment and possibly medication.

If you see a dramatic change in the person you love that lasts more than a few weeks, you have reason to be worried. Many married couples in this situation get stuck for years in helplessness and fear when they feel the person they love is no longer reachable. Self- blame and attempts to control or punish your spouse will not help the situation. When the changes are the result of serious problems with alcohol, sex or mental illness it is doubtful that you or your marriage are the cause.

It is important to let your spouse know how you feel about their behavior and how it is impacting your lives. Counseling is the best option, either for both of you or the person in need. Even if he or she is unwilling, you can still benefit greatly from seeing a professional who is knowledgeable about addiction and marital issues. Al Anon ( www.al-anon.alateen.org) 12 step groups are a wonderful way to strengthen yourself and learn healthy ways to address the problems you are facing.

Ann Smith is the executive director of Breakthrough at Caron, a five and a half day residential group therapy program designed to help adults shift destructive life patterns, improve relationships and foster personal growth. For nearly 30 years, her focus has been on addiction, family systems and experiential therapy. Ann has a Master's Degree in Rehabilitation Counseling and is licensed as both a Professional Counselor and a Marriage and Family Therapist in Pennsylvania. She is the author of two books titled "Grandchildren of Alcoholics: Another Generation of Co-dependency" and "Overcoming Perfectionism: The Key to a Balanced Recovery." Learn more at www.breakthroughatcaron.org.