I don't know about the question you asked, but I am sure there is some psychological reasons, backed by empirical evidence, that people prefer to be in relationships during certain times of the year. Also, more prone to commit suicide, and addicts and alcoholics are more probe to relapse.
Obviously things like that are exaggerated for music, social media, etc, but overall, I believe they are true to an extent.
Holidays have increased visibility from family, many people like a boyfriend/girlfriend to tag along. Many women feel pressure to be in a relationship, all year, but holidays would be esp. so. Also, the party/dating scenes shift into winter, people generally go out less, less options, less temptation, less chances.