There are two ways that a possible compromise rears its head - one is at the start of a relationship configuration, when everyone is working out what everyone's respective needs are, and the other are the day-to-day things.
For the first one, instead of repeating it, I'll refer you to a blog post I did a while back on how we did it. Here it is: "Getting Your Priorities Straight"
In terms of the day-to-day stuff, we each made a commitment to try to work to the greater good - and that means being willing to be flexible on things when one person is in exceptional need.
Understanding where YOU draw the line is very, very important.