Sentiment analysis (SA) is a technique aimed at extracting opinions and sentiments through the analysis of text, often used in healthcare research to understand patients’ needs and interests. Data from social networks, such as Twitter, can provide useful insights on sexual behavior. We aimed to assess the perception of Valentine’s Day by performing SA on tweets we collected between 28 January and 13 February 2019. Analysis was done using ad hoc software. A total of 883,615 unique tweets containing the word “valentine” in their text were collected. Geo-localization was available for 48,918 tweets; most the tweets came from the US (36,889, 75.41%), the UK (2605, 5.33%) and Canada (1661, 3.4%). The number of tweets increased approaching February 14. “Love” was the most recurring word, appearing in 111,981 tweets, followed by “gift” (55,136), “special” (34,518) and “happy” (33,913). Overall, 7318 tweets mentioned “sex”: among these tweets, the most recurring words were “sexy” (2317 tweets), “love” (1394) and “gift” (679); words pertaining to intimacy and sexual activity, such as “lingerie”, “porn”, and “date” were less common. In conclusion, tweets about Valentine’s Day mostly focus on the emotions, or on the material aspect of the celebration, and the sexual aspect of Valentine’s Day is rarely mentioned.