Boyfriend downloaded dating app

My boyfriend went out with friends and downloaded Hinge. I saw the app open on his phone this morning. We are in a monogamous committed relationship for almost two years. Everything is amazing. We have a trip planned at the end of the month. We love each other and tell each other all the time. We’re really focused on growing together as a couple.

He doesn’t know that I know that he was on the app. I don’t know what he was doing on the app. I didn’t look.

C: Boyfriend downloaded and opened hinge app
T: He isn’t telling the truth.
F: Worried
A: Plotting to find out more information, making plans to look at the app tomorrow to see what’s going on.
R: Don’t trust boyfriend?? *I’m not sure if this is the result.

New model:
C: Boyfriend downloaded and opened hinge
T: I can trust him **is this completely delusional? Is this a good thought in this model?
F: Loving
A: Do things for him. Love on him.
R: Create a stronger relationship.

Alternative new model:
C: Boyfriend downloaded and opened hinge
T: Everything is always working out for me, for my good, and in my favor.
F: Safe. At peace.
A: Live my life. do nothing with the situation.
R: Continue to feel the feelings I want to feel regardless of what is happening with him. *I like this, but it this the result?

My brain wants to search for answers to be absolutely sure that he’s not going to start dating people outside of our relationship. That would be a deal breaker for me and I want to know sooner rather than later so that I can face the issue. Thanks for your help.