Both low beams stopped working at same time. Common cause?

Yeah, I bought a 10 pack on ebay for 8 or 10 bucks and kept them in my glove box. I drove a little over 200 miles per day for a few years commuting to work every day, leaving early when it's dark and getting home late when it's dark. I'm sure because of this, I used my headlights a LOT more than the average person so they burned out more frequently maybe?) but I got to be pretty quick about swapping them at a gas station or on the side of the road when I saw the "flash" of them burning out lol

New sockets didn't help me so I got to where I put new spade terminals on the wires and plugged the wires directly on to the back of the bulb. That didn't help any either so I don't think it was a connection issue, just a poor design causing them to overheat is my theory. especailly on long trips (I drove a little over 2 hours each way).

Once I started working from home my headlight problem improved significantly. Not only because I didn't drive nearly as much, but also because my trips were short 20-30 minute trips instead of driving the car 4-5 hours per day.
 
Both low beam headlights on my daughter's '03 Protege5 stopped working at the same time last night. Both bulbs have been replaced within the last year. High beams on both work fine, parking lights and flashers work fine, but no low beams.

Also, at about the same time the lights quit working, her the battery light on her dash coincidentally came on too, briefly. She was on the interstate at that time.

I'm thinking either the headlight relay, or the headlight switch itself. A relay is only $21, but I hate blindly shotgunning parts, for nothing, and wanted to ask if this is a common problem, and if so, what the common cause is. If I don't get any leads, I will go ahead and try the relay, but if the headlight switches or something else is a common problem, then I'd rather try look into that first.

I spent months and months going through a lot of wiring trying to find out why I was blowing bulbs within hours of install and 3 brand new batteries in less than a year. come to find out my + line to the alternator was poorly done by a previous mechanic (which I no longer use...) and was causing massive amounts of feedback to my battery causing the power terminal on the battery itself to literally smoke...
not saying this is the same issue, just giving you a personal perspective.
I ran completely new battery wires (both +/-) with new all copper fittings, coupled with an optima red and as far as I can tell all those issues went away.
 
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