The attitude-behavior gap and intention-behavior gap has not been research extensively. The purpose of this study is to provide a review of moderating or mediating factors on the relationship between intention or attitude and behavior of sustainable tourism. Intention was defined as the degree of a human being’s resolve to perform a certain action. The construct ‘Intention” has been used widely in some theories like the Theory of Planned Behavior. Researchers usually include the intention construct into their research framework to explain the theoretical mechanism. Sustainable or ecological tourism education has been implemented for years and empirical evidence provides us that almost all tourists are alerted to the importance of sustainability. There is a great challenge that tourists’ behavior might not concur with their intention. Policymakers and marketers really want to know the real factors affecting the association between the intention and behavior of sustainable tourism. Tourists’ purchase intention is a rational process and is affected by safety. Tourist behavior is associated with price and service environment which is a mixture of rational and emotional considerations.

Fear of missing out (FOMO) refers to the customer's perception of being anxious for not engaging in an experience. FOMO is an anxiety feeling positively associated with social media usage that one cannot catch up on something important in life. Fear of missing out (FOMO) marketing appeals initiated from social media usage were found to significantly affect consumer purchase decisions including choice of destination. Consumers usually browse social media and social networking sites such as forums and reviews in online tourism agents (OTAs) when they make travel decisions. Although FOMO is expected to affect tourists' perception and urgency in making a tourism decision, the use of FOMO-laden message to promote travel destination through different types of influencers has not yet been widely studied. This study fills this research gap by examining the effect of using FOMO laden content to promote travel destination through different types of influencers. An online experiment was conducted with four experimental conditions in which different influencers share about a destination using the same FOMO-laden message: (1) travel KOL, (2) tourists who post user-generated-content (UGC), (3) personal friends, and (4) a control condition with the absence of influencer and FOMO message. The 984 respondents were randomly assigned into one of the four experimental conditions. Data collected was analysed using PLS-SEM and PLS-MGA. Results indicated that anticipated elation, anticipated envy, and social influence predicted 30.2% variance of FOMO and FOMO explained 31.6% of variance of intention to visit the destination promoted. Multi-group analysis (PLS-MGA) found that exposure to message shared by travel KOL and personal friends significantly strengthen the FOMO feeling of participants resulting in strong intention to visit the destination promoted. UGC posted by tourists showed similar effect as the non-FOMO laden control group and are less significant in driving the FOMO feeling that leads to visit intention. Findings of this study provide insights into how effectiveness of destination promotion can be enhanced by using FOMO-laden message on social media through influential influencers.