As social network sites (SNS) expand the boundaries of one’s social life, we often observe encounters between two different types of motivations for socialization - I want-to socialize vs. I have-to socialize. SNS at present are considered commodities. People do not always start using SNS because they want to, but often because everyone else is using it; people do not wish to be isolated from social circles. This study aims to examine different types of user motivations in SNS and observe how these lead to actual socialization behaviours with different progress dynamics. We apply constraint- and dedication- based relationship framework to distinguish motivations and identify constructs for each motivation. We plan to collect data from one of the major SNS to validate how their socialization intentions are differently realized into actual behaviours. We develop a two-staged research model and this research-in-progress presents the result of the pilot study conducted for the first stage. We also discuss how the second stage of the study will be executed, and how it will benefit the related literature when the project is successfully completed.