You see that the little thumbnail of a profile picture has two people in it.
Often you’ll find that the reason it bothers you is because you have taken his actions as some sort of reflection on you and the past you shared together.
When you've shared your life with someone, it can feel excruciating when you learn he's now enjoying his favorite sushi restaurant with another person.
It's important to move past this feeling, as otherwise you risk becoming an amateur detective who is focused on her ex's life to the detriment of her own.
Learning the details will only increase your queasiness.
Cultivating a 'c'est la vie' attitude toward life can help you to move through this painful situation.