I might be being daft but I have various bits of jewellery that feature hearts in some way (those Tiffany/Paloma Picasso earrings everyone used to have, pair of very pretty little pavé heart studs, couple of other bits) and I never wear them because I feel like hearts might be a bit childish. I'm late 30s and subscribe to the Meghan Markle school of understated jewellery
If you saw someone my age wearing heart jewellery would you think it looked a bit odd?