The ideal standards model predicts linear relationship among friendship standards, expectation fulfillment, and relationship satisfaction. Using a diary method, 197 participants reported on expectation fulfillment in interactions with one best, one close, and one casual friend (N = 591) over five days (2,388 interactions). Using multilevel modeling, our study found that hypothesized relationships were moderated by participant sex. For males, ideal standards had a curvilinear relationship with expectation fulfillment, where higher standards were associated with less fulfillment, but both expectation fulfillment and standards directly predicted satisfaction. For females, ideal standards linearly predicted expectation fulfillment, but an interaction between standards and fulfillment predicted satisfaction. Implications for the relationship between ideal standards and sex on friendship maintenance and satisfaction are discussed.