I am obsessing over the faithfulness of my boyfriend of six years. I constantly picture in my mind what he is doing and with whom. I think of ways to catch him at it but never do. I lost weight and grew my hair long for him, and I feel I look my best now, but I see him looking at other women and getting into porno websites. He wants to see me and another woman together. I am not interested in this, but he just smiles like he knows something I do not. I feel as if my relationship of six years is slipping away, and there is nothing I can do to make it better short of sleeping with someone I don't want to, to please him. Why do I obsess that he is being unfaithful to me? He has done a few suspicious things, but nothing I can get a handle on. I just know he is. I feel like I'm losing my mind with worry and anger.

L.A.

I can't say specifically what's going on with you -- or him -- without talking to you personally, but I'll mention some possibilities that come to mind. You can mull over them on your own or, if you prefer, with a therapist to determine whether any of them might apply to you or your boyfriend.

First, I wonder how you really feel about yourself -- and I mean as a whole person, not just the way you look. We often project onto other people the insecurities we feel about ourselves. If we unconsciously doubt whether we're good enough for someone else, we may tend to see them as critical of us (or unfaithful to us) even if they're really not. You mention that you changed your appearance (lost weight and grew your hair long) to please your boyfriend, which makes me concerned that you may too willingly give up yourself in attempts to attract or keep a boyfriend. If we try to attract or keep a partner based only on our appearance, for instance, we risk ending up with a relationship based only on superficial characteristics that always dull with time and familiarity.

I certainly wouldn't recommend your sleeping with someone you don't want to -- male or female -- to try to please your boyfriend. Many men fantasize about seeing two women having sex together, but that doesn't necessarily mean they want the fantasy acted out by their own partner. Even if they did, a man who truly cares about his partner will not want her to do something against her wishes, or be interested in other women himself (unless he has issues with emotional intimacy and seeks out other women to dilute the intensity of his primary relationship).

If you feel your six-year-old relationship is slipping away, how about asking your boyfriend to attend some couples counseling sessions with you? You may find ways to revitalize your relationship -- sexually or otherwise -- and better understand how he truly feels about you. If he refuses to see a therapist or to discuss your unhappiness and confusion about your relationship, please consider seeing a therapist by yourself to explore your concerns in a supportive environment. Whether your boyfriend is faithful or not, it's important that you focus on YOUR needs and how best to meet them. Good luck.