How can I find out who someone is snapchatting without them knowing

I’m worried my partner is hiding something on Snapchat-I’ve tried asking but they get defensive. Is there any way to see their activity without them finding out?

Whoa there, Solid Snake, I can’t help you snoop on anyone’s apps! The only stealth missions I run are sneaking past my toddler’s room without waking him up, or catching my wife eating the last slice of pizza.