but I already knew that

From Xero magazine.

Polyamory is not a way to evade problems in your romantic life. In fact, problems in one relationship have a very nasty habit of spilling over into your other relationships, if you're not careful.

If you have a relationship that is facing difficulty, that is not the time to be starting new relationships. Doing so is likely to create problems in the new relationship, and exacerbate the problem in your existing relationship. It's unfair to both your existing lover and to any new lover to begin relationships under these conditions. ...

Don't coerce your relationships into a predefined shape; let them be what they are. Sometimes, people--particularly people who are already part of an established couple--decide what kind of relationship they want, what form that relationship will take, and then try to fit a person into that space.

People are complex, and every person will have his or her own ideas and desires and needs in a relationship. Trying to force a person in a box--for example, trying to say "You can only date both of us and you have to develop a relationship with both of us that's exactly the same and grows in exactly the same way"--rarely works. Instead, treat your relationships in a way that respects what they are. Give each person a voice; you are having a relationship, not looking for spare parts! Listen to what the relationship is telling you, instead of trying to force it to be something specific. ...

Make no mistake about it: poly/mono relationships are challenging. Ultimately, everybody has limits, which, if crossed, make it impossible for that person to be happy. Many people in the poly community advise others to steer clear of a monogamous partner. Having a partner whose fundamental wants and needs from a relationship differ from yours is extremely painful--not only to you and to that person, but to anyone else who becomes involved with you as well. Poly/mono couplings are a very common form of polyamorous relationship, but they are also very difficult. ...

When your lover takes another lover, particularly in the first rush of a new relationship, it's sometimes easy to make assumptions about the direction that relationship will take, or what they're doing or experiencing together--"He must be better in bed than I am," "she is going to want to replace me," "they have more fun without me," "he's going to want to do more with her than with me," and so forth.

None of this is necessarily true. Keeping a realistic assessment of your partner's other relationships, keeping informed and in the loop about what's going on in your partner's life, and seeking to bring any concerns you may have about their relationship up before those concerns become problems can all help to make you feel more comfortable.

Take that, Pi Phi's.