From 2020 to 2021, Marion County, Indiana, USA, saw an increase in early syphilis diagnoses, primarily among gay, bisexual, and other men who have sex with men (GBMSM). This rapid ethnographic assessment combines survey data from GBMSM with data from key informant interviews with multiple groups of stakeholders, including GBMSM, to describe how COVID-19 impacted sexual behaviors, sexual decision-making, and access to sexually transmitted disease (STD) services among GBMSM in Marion County, Indiana. A total of 62 virtual, semi-structured qualitative interviews with 72 key respondents including health department staff, medical providers, community-based organization staff, and GBMSM were conducted from October 14 to November 22, 2021. Modifications to partner-seeking and sexual behaviors attributable to the pandemic were associated with the way in which individuals reacted to the pandemic in general. Some GBMSM adopted mitigation strategies to avoid COVID-19 when meeting sex partners, such as creating a "sex pod." Effects on mental health included increased loneliness, heightened anxiety, and a sense of hopelessness regarding the perceived inevitability of acquiring COVID-19. For some, the latter prompted decreased engagement in preventive measures when engaging in sexual activity. The pandemic decreased access to STD services and significantly curtailed public health outreach efforts, which may have limited access to needed STD treatment and care. Efforts focusing on ongoing public health concerns during extreme health events like COVID-19 may want to consider the many ways these events affect ancillary behaviors, such sexual decision-making and sexual behaviors. The role of mental health is key; messaging and guidance may benefit from a trauma-informed approach.