Katie Bolin started seeing her boyfriend in December of 2013. But when February rolled around, he didn't want to make plans for the 14th.

"I've never been that big on Valentine's Day, so I had plans with friends," Bolin said. "But then on Valentine's Day, he was texting me saying he felt bad" they wouldn't be together.

The two had met through mutual friends and began keeping in touch on Twitter, but they weren't dating. For months, they were just "hanging out."

"Hanging out is like the pre 'we're dating,' " Bolin said. "Putting the word 'date' on it is stressful — a hang-out is so much less pressure."

For many millennials, traditional dating (drinks, dinner and a movie) is nonexistent.

In its place, young people hang out or say they are "just talking." So when store windows fill with hearts and chocolates and red roses, young couples feel pressure to define their ambiguous relationships.

That's not easy, in part because traditional dating has changed dramatically — and so has the way young people talk about relationships.

Twenty-year-old Kassidy McMann said she's gone out with a few guys, but it wasn't as serious as dating. "We just called it hanging out," she said.

According to McMann, the widespread fear of rejection among millennials has drawn them to the more casual hang-outs because "they don't want to have to go through breakups or get hurt."

Kathleen Hull has a more scientific explanation. Hull, a University of Minnesota associate professor of sociology, said that an extended adolescence has altered the dating scene.

The "traditional markers of adulthood" — marriage, children and home ownership — now occur later in life than, say, in the 1950s, when going steady in high school often led to marriage.

Now, "there's this long period between going through puberty and getting married that would be a long time to be dating," she said. "It's a longer period of transition to adulthood."

Focus on school

Twenty-somethings who don't go to college tend to enter into the adult world more quickly, said Hull. But most college-educated millennials say they have no plans to settle down in the near future.

"The actual meaning of dating, at least for college students, has changed," said Hull. "The practice of dating in the traditional sense has nearly vanished from college campuses."

Karl Trittin agrees. "Most students don't have time to get into real relationships," said the freshman, who's studying economics at the University of Minnesota. "It's like taking another class."

When young people do get together, "it's like dating back in the '90s, like you see on TV shows," said Cory Ecks, a University of Minnesota marketing senior. "It isn't necessarily exclusive. It's casual."

College students often choose to be single while pursuing degrees, as do recent grads who are trying to launch careers. Instead of seriously dating, they dabble in various kinds of casual encounters.

"A lot of people are into 'things,' " said McMann, a sophomore at the University of Minnesota. "They want someone to cuddle with and make out with, but they don't want to date them."

Learning to date

"Hooking up" has been blamed for changing the dating landscape, but Hull said the practice is nothing new.

"It really started with the baby boom generation," she said. "It's only more recently that the term hooking up has come into common usage."

And despite the hype about hooking up, research shows college students aren't having casual sex at higher rates than the coeds before them, according to Hull. On the contrary, rates of sexual activity among university freshmen are similar to the rates in the mid-1980s.

But the John Hughes-era of romance has changed in other ways.

"Going on a date now has more significance, when the option of hooking up or just hanging out in a group-friend setting is more prevalent," Hull said. "When people say they're dating someone, it usually means they're in a relationship."

After college, millennials who are finally ready for a serious relationship might be surprised to learn that they don't know how to go about it.

"It's not until they leave college that some people go back to the idea of using dates as a way to check out potential partners, rather than a way to get into a committed relationship," said Hull.

That's fine with Bolin, now 27. The Minneapolis artist and musician said that with less pressure to get married and have kids early, "your 20s are a time where you don't really know what you want." But when you've reached your late 20s, dating — in the old-fashioned sense — may be the best way to find a compatible partner.

"Dating has always been hard and always will be," Bolin said. "But I've asked guys out before. It's not that scary, it's kind of empowering."

Libby Ryan is a University of Minnesota student on assignment for the Star Tribune.