After personally researching this claim that "most people fall in love during times of emotional vulnerability." I have found it to only be partially true. Studies have shown that acting out of vulnerability can increase feelings of closeness and attraction but doesn't immediately jump to love or being infatuated with someone. A 2008 University of Chicago study found that being emotionally open helps to strengthen bonds through trust, but it doesn't automatically guarantee romantic attachment (University of Chicago News.) Similarly, a 2019 Frontiers in Psychology article disclosed that people who express vulnerability are often found to be perceived as more authentic and genuine partners. Therefor, being more desirable, but attraction does still depend on mutual interest and timing (Frontiers in Psychology.) Secondary sources such as Psychology Today supported this idea, by saying that vulnerability enhances feelings of intimacy but shouldn't be mistaken for a formula for love (Psychology Today.) While all of these sources are credible, Psychology Today may simplify their research for the public, which can exaggerate the emotional impact of vulnerability. Overall, the evidence supports that vulnerability deepens emotional connection between two individuals but undermines the idea that it actually causes love. The original post where I found this claim didn't include an author, and after reaching out through the site's contact form, I received no reply.