My condolences on the passing of your husband.
I don't necessarily agree that new trucks are less reliable, especially since the Ram 1500 just recently was found to have the best, three year reliability.
That being said reliability can suffer with the more intensive use of electronics, but that applies to all makes. Currently, you can purchase a new Ram 1500 Big Horn in Quad Cab with a 5.7 Hemi V8. the only big difference between your current truck and a new one is a system called eTorque, which is a Start/Stop function. This has shown to be problematic, especially in earlier builds.
Generally, though, miles affects reliability more than mere age.
I'm guessing you are looking for piece of mind and that is what has triggered your inquiry. A new truck would provide you with a warranty, but you're current truck may be in exceptional condition and still have a lot of life left. You then need to find the balance between piece of mind and the cost of a new truck (be prepared for sticker shock).
I would suggest having a reliable auto technician examine the current truck and give you appraisal on condition as a starting point before you consider something new.
Best of luck,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 147030 miles.