Your BF has 44,760$ left in payment on a 4 year old truck. This figure is flabberghasting! That is like a mortgage!
Now that this is out of the way, you(i.e., your boyfriend) has to decide whether he wants to be on the hook to pay 44,760$ TODAY for a 4 year old truck. If he thinks this is crazy (he should), he has to sell it because keeping it is doing exactly that. A sunk cost is a sunk cost.
Does your BF need a truck(as in for work hauling big rigs and tools)? If not, this is even crazier.
Assuming a shortfall of 14K$, and a luxurious replacement vehicle of 10,000$ (used fuel efficient car with moderate mileage), you would be 24K$ in the hole. That is an improvement of 15K$. It is like being paid to "downgrade" to a less clownish car. Plus you would reap the benefits of better fuel economy.
If a truck is needed for work, your BF should ask for a raise because he apparently can't buy it on his current salary.