The need to keep tons of things for "sentimental" reasons. The inability to get rid of anything. Usually involves the need to rent storage lockers, because every room in the house and basement is already filled with sentimental knick-knacks and memorabilia.
When Jane moved out of her house, she needed to rent 3 storage lockers to store all of the things she couldn't part with. She suffered from SentimentalRetardation.
The one that gets attracted to people and starts paying attention to every little thing they do, even without realizing it themselves. The ones that either tell the person and get rejected or not tell them at all, but still love and care for the person with all their heart.
A physiological glitch where your adult body has a romantic reaction to a childhood memory. It occurs when you see a vintage photo of a child actor you loved in the 3rd grade, and your brain accidentally reboots your original hormones from 2007. It’s essentially the "ghost of crushes past" haunting your pants.
"I was scrolling through a 'Throwback Thursday' thread and saw a picture of Miranda Cosgrove from the early iCarly days. I got a total sentimental boner. It felt like my adult self was high-fiving my 10-year-old self across the space-time continuum."