Cards and roses have given way to tweets and emoticons on Valentine's Day, as modern behaviors increasingly lead to a more isolated and depressed society, social scientists say.
More hours online, less face-to-face time and less sex -- these patterns of behavior only increase feelings of loneliness and depression, they say.
"It's very distressing to me to see couples walking down the street holding hands and in the other hand is a cellphone. How can you give that divided attention?" said Tiffany Field, director of the Touch Research Institute in the Pediatrics Department at the University of Miami School of Medicine.
Although no rigorous scientific research has focused on whether technology directly interrupts relationships, she said, it's impossible to ignore: In restaurants, airports and outdoor spaces, people turn their attention to smartphones.
Overall, Americans' well-being is on the decline, according to a Gallup poll that measured people's attitudes about feelings of purpose, social relationships, financial security, community and physical health. General well-being was measured at 61.5 last year, down from 62.1 in 2016.
The poll found declines of well-being in 21 states, the largest number recorded in the survey's 10-year history. Not a single state showed statistically significant improvement compared with the previous year. Pollsters called the finding unprecedented.
Jean Twenge, a psychology professor at San Diego State University, focuses much of her research on cellphone use among teenagers and how it affects their mental health.
In her book "iGen: Why Today's Super-Connected Kids Are Growing Up Less Rebellious, More Tolerant, Less Happy -- and Completely Unprepared for Adulthood," she discusses rising rates of depression among teens since 2012, after years of stability, at the same time smartphones saturated the market.
In subsequent research, she found that people who spend five hours or more on their smart devices are substantially more likely to have feelings of depression and suicide ideation. On average, teens and adults are spending six to eight hours online, she said.
"That is so much time, it has crowded out the time people used to spend interacting with each other face to face," Ms. Twenge said.
Another worrying trend Ms. Twenge found was that adults in the '00s were having sex nine times less than those in the 1990s. She published her findings last year in the journal Archives of Sexual Behavior.
Controlling for variables such as an aging population or a trend toward marriage later in life didn't fully explain the results, said the researcher, adding that logic points to the increasing pervasiveness of smartphone and computer use.
"It's not just teens staring at their phones when their partners are trying to talk to them -- it's adults too," she said.
This lack of face-to-face interaction and physical intimacy is known to have detrimental health effects. Much of Ms. Field's research at the University of Miami has focused on the importance of touch on the physical and mental well-being of the individual.
Holding hands, hugging, anything that moves the skin in a meaningful way increases the neurotransmitter serotonin (which is key in feeling pleasure) and the hormone oxytocin (which is key to feeling close to another person) throughout the body, and decreases stress levels.
"It's very important to be out there hugging your friends and showing physical affection to anyone who's close to you," she said.
"It makes you feel better. It also has this huge effect on your physicality -- it warms your body and slows down your stress level so that people are calmer and they feel better."
People who aren't able to get the physical intimacy they need from close relationships are starting to look elsewhere, Ms. Field said.
A marker of this growing problem is the rise in popularity of cuddle parties and cuddle therapy, she said. This is either a party of strangers who lie in a dark room holding one another for a few hours or a paid session of nonsexual physical intimacy with a therapist.
"I've been getting a lot of calls on those. They're happening all over the world now," she said. "That itself attests to the fact that people are being touch-deprived if they need to go to cuddling parties with total strangers."
Absent a partner, people can still find ways to get the benefits of touch with other activities. Among Ms. Field's research, exercise, fast walking, a massage and yoga were all seen to have equal benefits of releasing happy hormones of serotonin and oxytocin and decreasing levels of the stress hormone cortisol.
Likewise, Ms. Twenge suggests increasing face-to-face interaction with people instead of texting and sharing on social media.
"We know from decades of research that interacting with people face to face is good for mental health and for guarding against loneliness," she said.
Her advice is to decrease cellphone and internet use to two hours during leisure time to allow for focus and attention on real-world activities.
"Instead, do all of the real-life things that we know are linked to happiness -- like spending time with people in person, sports and exercise, sleep, and if you have a partner and you want to, sex."