You can't really predict where a FWB relationship will go, which might be appealing to some people, but it's definitely a good idea to set some ground rules. "It's important for people in friends with benefits relationships to establish limits, rules, and boundaries in the interest of no one getting hurt," Dr. Lehmiller says. For example, you might make a pact not to tell each other when you're seeing other people. Or you could tell your FWB that you want to be open about the other people you're seeing, as long as you're comfortable with it. "This will reduce the odds that you'll be caught off-guard later on," Dr. Lehmiller says. In Ilana and Lincoln's case, she wanted to know all the dirty deets about his sex life with other people, perhaps as a defense mechanism to mask that she really wanted something more.