Questing for books is never weird! I'm glad you're looking to get back into reading.
I haven't read Flipped, but based on the description I have a few suggestions that might be up your alley but also appropriate for an adult reader:
The Time Traveler's Wife by Audrey Niffenegger. Essentially a tragic love story about two people whose entire lives are entwined because one of them accidentally time travels to different points in the other's life. Kind of a wild concept but the characters are very realistically drawn.
Station Eleven by Emily St. John Mandel. It tells the story of different people surviving and thriving in a post-apocalyptic world after a deadly virus wipes out most of the population. While it's got that sci-fi backdrop, it is very focused on the characters and how they care about each other, so I found it far more uplifting than a lot of apocalyptic fiction out there.
White Oleander by Janet Fitch. One of my favorite books when I was a teenager, although I think it's an adult book. About a teenage girl who ends up in the LA foster system once her mother is arrested for murder. Very heart-wrenching in spots but it's essentially about how she learns who she can trust and that some people are worth it while others aren't. I've read this one over and over. The writing is really beautiful.
Anything by Alice Hoffman focuses a lot on human relationships, often with a subtle helping of magical realism. My favorites are Property Of and Practical Magic, and The River King was quite good, too.
White Teeth by Zadie Smith tells the story of two very different London families and their relationship with each other. That description sounds boring but I couldn't put the damn thing down when I read it. I believe the author wrote it when she was only 25 as well, which made me turn green with envy.
I could go on but that might be a decent selection for the time being. Check these out and see what appeals to you. I wish you the best of luck – it is never too late to rediscover the love of reading!
P.S. I was having trouble posting this so if it suddenly shows up like six times I am going to be pissed. My apologies.