The phrase "it sucks, but sometimes you have to" is being used in various contexts to express frustration or disappointment with certain situations. However, the specific topic or issue being referred to is unclear, as the phrase is being applied to a wide range of subjects, including parenting, backpacking, sports, and more. It appears that the phrase is being used to acknowledge that some things in life are unpleasant or difficult, but may be necessary or unavoidable.