My 17-year-old daughter has dated a few boys in high school. I know the relationship is getting serious when I see her wearing their hoodie.

• I know my daughter is dating someone when she starts wearing their hoodie. 
• I didn't know this was a thing, and she had to explain it to me the first time. 
• Some hoodies have been returned, others cut up, and one is still in our guest room. 

The first time I saw one was the summer before my daughter's freshman year of high school.

"Where did you get that?" I asked. She was wearing a clearly pre-owned hoodie that I had no recollection of buying.

"Oh, it's Ben's," she said, mentioning the name of the boy she'd been talking to.

"Why are you wearing it?" I questioned, perplexed that she was wearing it not only because it was a boy's but because it was stiflingly hot outside.

"That's what you do, Mom. You wear your boyfriend's hoodie."

I blinked in surprise, two things in our conversation standing out to me. First, she and this boy had moved from the talking stage to being boyfriend and girlfriend. Second, I had no idea it was popular nowadays to wear your boyfriend's sweatshirt.

I wore my high school boyfriend's ring around my neck

When I dated my high school boyfriend in the last millennium, I wore his class ring on a necklace for a semester. It made me feel closer to him and was a visible symbol that I was dating someone. I stopped wearing it because it was a behemoth of a ring and uncomfortable clunking against my chest.

Back then, it was also commonplace for girls to wear their boyfriend's varsity letter jacket or sweater. I knew several girls at my high school who did that, as well as classic movie characters from my youth, such as Sandy in "Grease" and Cindy Mancini in "Can't Buy Me Love."

As it turns out, there's actually a scientific reason girls wear their partner's clothes, whether a hoodie like Gen Z prefers or a letter jacket as in the past. A 2018 study from researchers at the University of British Columbia found that women who wore something with their boyfriend's scent felt calmer and had lower anxiety and stress when compared to women who wore something with a stranger's scent.

Hoodies disappear when the relationship ends

My daughter's new-to-her hoodie disappeared from her wardrobe a few weeks later. As did talk of Ben. I would learn that the breakup was amicable and his hoodie had been returned.

Another hoodie appeared about six months later and stayed around longer. This time, not only did the hoodie make an appearance in our house, but so did the boyfriend, who hung out with my daughter most weekends.

This was my daughter's first serious boyfriend, and the amount of time she spent wearing his hoodie seemed proportionate to the seriousness of their relationship. When the relationship ran its course, the hoodie and the boyfriend stopped showing up at our house.

My daughter is 17 now, and a couple more hoodies haven't fared as well as the first two. One hoodie ended up underneath her bed, cut into little pieces. That hoodie belonged to a boyfriend who cheated on her. The phrase "Hell hath no fury like a woman scorned" came to mind when I stumbled upon the shredded pieces.

Yet another hoodie remains in a bag in our guest room. My daughter wanted to give it back, exchanging it for the hair scrunchies she'd given this particular ex to wear on his wrist (another symbol of Gen Z coupledom). But the pain of this breakup and perhaps the finality of returning the hoodie have hampered any chance of a meet-up. There's talk of donating this hoodie the next time we make a run to Goodwill.

I have no idea when the next hoodie will appear. It may be merely a phase or a fad. I hope eventually she finds one that is exciting yet comfortable, complements her, and lasts.