My boyfriend and I had a red heart emoji on Snapchat and now it’s a smiley face. He’s the only one I Snapchat. Does this mean he’s cheating on me?

We have not recently been snapping much, but today I noticed that the red heart emoji changed to a smiley face. Can that be just from inactivity between us or does the red heart emoji only switch to a smiley face when you’ve been replaced as a best friend? I brought this up to him and he screenshotted his Snapchat list to me, but I’m panicking and afraid he might have deleted a thread.