This is dumb. Young couples have been plagued by insecurity long before location sharing. Dial the clock back 20 years and I'm your typical high school boy worried about his girlfriend.
I share my location with my wife, and even some buddies of mine. My wife has seen my location when I was at someone's bachelor party. It has nothing to do with sharing location and everything to do with trust in your relationship. I don't have her location to keep tabs on her. I have her location so we can better figure out how to get our kids from places. I have my buddies' locations so if I end up grabbing a beer, I know who's out and about, or when someone goes to Tanzania, I can say, Joe, what the hell are you doing in Tanzania?
Before location sharing you texted, or you called, or you hit me on my pager, or sent me a letter. Technology isn't the problem, it's -- once again -- just us dumb people being dumb.