2012 Jeep Patriot Overheating

Hello,

My car is overheating. The needle takes it time getting to the middle but after
about 15 minutes of driving it will go almost to 3/4 of the temperature gauge
even when driving only 60km/h our so.

The issue happened about 2 months ago at which point I replaced the
thermostat housing and both thermostats. It ran fine for about a month and
then began overheating again. I then replaced the radiator, again replaced the
thermostats and flushed the cooling system. Once, again the car ran fine for a
month and then began overheating again last week.

It takes about 15 minutes to warm up and then it gets to almost 3/4 of the
temperature gage without driving more than 60km/h. The coolant level is good.
The car heater works properly (and even cools the engine down when on).
There is a little bit of dirt and specs in the coolant, but nothing crazy. The oil is
not milky and no oil in the coolant. The radiator fans turn on properly. The
lower radiator hose does not get super hot, I can hold it after the car has been
running.

My guess is that I should replace the thermostats again and flush the cooling
system, but could that really be the same issue again? It seems very strange to
me that the thermostats could get stuck open 3 times in as many months.
Could this be a symptom of another issue?

Any help would be appreciated!

Michael