coffee addict-
Tzipporah was a young girl tending her father’s sheep and certainly much younger than the nearly 80 year old Moshe, and Osnas may have been the daughter of Dinah, who herself was only around the age of Yosef.
If you’re looking for a similar age shidduch in the Torah, it’s Adam and Chava. She was still younger though. After that the gap just grew and grew.