https://journals.sagepub.com/doi/10.1177/0265407520927469

Interesting quotes:

"Reciprocation of attraction—people’s tendency to like those who like them—has long been theorized and shown to promote relationship initiation (e.g., Aron et al., 1989; see Berscheid & Reis, 1998, for a review). Immediately reciprocating another person’s expression of liking, however, is not always the most effective strategy for attracting mates. Indeed, people who are too easy to attract may be perceived as more desperate and thus as less valuable and appealing than those who do not make their romantic interest apparent right away (Eastwick & Finkel, 2008; Finkel & Eastwick, 2009)."

" What has been shown in romantic settings is that people are more attracted to prospective partners who are selectively hard to get (i.e., easy for them to attract but hard for others to attract) than to those who are uniformly easy or hard to get (Finkel & Eastwick, 2009)."