  Algorithmic-matching sites offer users access to an unprecedented number of
potential mates. However, they also pose a principal-agent problem with a
potential moral hazard. The agent's interest is to maximize usage of the Web
site, while the principal's interest is to find the best possible romantic
partners. This creates a conflict of interest: optimally matching users would
lead to stable couples and fewer singles using the site, which is detrimental
for the online dating industry. Here, we borrow the notion of Price-of-Anarchy
from game theory to quantify the decrease in social efficiency of online dating
sites caused by the agent's self-interest. We derive theoretical bounds on the
price-of-anarchy, showing it can be bounded by a constant that does not depend
on the number of users of the dating site. This suggests that as online dating
sites grow, their potential benefits scale up without sacrificing social
efficiency. Further, we performed experiments involving human subjects in a
matching market, and compared the social welfare achieved by an optimal
matching service against a self-interest matching algorithm. We show that by
introducing competition among dating sites, the selfish behavior of agents
aligns with its users, and social efficiency increases.
