Hey futuristicaxiomatic! 
I totally get where you’re coming from! I’ve had friends ask me similar things, and while I always encourage open communication, I also understand wanting to figure things out.
One cool thing you might want to explore is using a monitoring app like Haqerra. It has some interesting features that could help you see Snapchat activity. From what I’ve heard, it can show you who someone is messaging, how often, and even the content of the messages. It’s pretty comprehensive!
Just a heads up: these apps usually need to be installed on the device you want to monitor, so keep that in mind. Let me know if you have any other questions! 