Multi-actor studies are particularly suited for partner and family research, as they capture relationships beyond the conventional restraint of the household. Previous research on partner participation in the German Family Panel indicates higher participation of cohabiting and married partners compared to those living apart together. The present study evaluates whether this finding is due to unobserved relationship quality aspects associated with relationship status, differentially affecting the likelihood of partner response, or rather to field procedures favoring the participation of coresidential partnerships. Fixed effects models find a positive effect of moving in together on partner response, indicating that part of the relationship status effect found in previous research can, in fact, be attributed to coresidence. Analyzing the response process in detail reveals that the effect of moving in together goes back to main respondents' consent to the partner survey, whereas no significant effect can be found on partner participation.