You should be careful when doing this anytime you invite a third party into your bed you are taking a chance of losing your man, in every relationship there should be boundaries and just considering a threesome is crossing those boundaries. Ask yourself, "What is sex with this other woman is much more enjoyable for my boyfriend?", or "What if he likes it so much that he wants threesome all the time?" If you really want to do this then you should find a woman that will not cross any boundaries other than fulfilling your boyfriend sexual fantasy and also that your boyfriend doesn't cross any boundaries also. Him wanting a threesome could mean many things, he may just want to try it once to fulfill his fantasy, he could have a sexual addiction, whenever you invite someone else into the relationship you always run the risk of losing your mate but you have to set rules and limits which should indicate each individual's comfort levels which should be understood and respected. Your relationship with your mate might be affected by this experience so you ought to clearly get what is comfortable for you and what is not. For instance you might be uncomfortable with him giving oral sex or penetrative sex to woman. Do not go beyond the limits. Keep in mind that you could get jealous so try as much as possible not to be doing this just to satisfy you man you have to be satisfied also. You might end up feeling jealous if the attention is not centered on you and you have to share your boyfriend.
You want to make sure that if you do have the threesome that you won't have any feelings of jealousy and betrayal. The people who often have problems after a threesome are often the ones who are very deeply involved with their mate emotionally. Jealousy often arises after threesomes whether its because your partner is being intimate with someone else, or you feel like your mate has cheated on you right in front of your face. If the third person involved is a friend rather than a stranger, the friendship could be affected or even ruined because now you feel you cannot trust them so make sure it isn't a friend. Some people permanently lose respect for their mate after a threesome, this is because some people view it as a test of their mates loyalty to them but when they feel like their mate showed too much attention to the third party and not them the rules and boundaries of been breached. If you're the type that is too emotionally involved with your mate, then threesomes are not for you. Unless, of course, you want to get your heart broken. If you still decide to do this then with most sexual activities, its best to practice safe sex. Odds are, you're not too sure about the sexual activities of the third party unless you know them personally, the act may be satisfying and pleasant, neglecting to take care of your health is something that can have terrible consequences. now with all of that being said:
If you and your partner are thinking of participating in a threesome, make sure that both of you are truly comfortable with it. There will be very hurt feelings and feeling of obligation if one partner is doing it merely to please the other. Communicate your wants and fears with your boyfriend before you decide to have a threesome. Make sure that no one feels left out. Everyone should be given sexual attention, and everyone should experience being both on the giving and the receiving end. Its not really a threesome if not everybody is actively involved in the process.