Most Helpful Guy
If it was as small of a thing as you say it is, there's either a bigger picture you're missing (like he has a complex about anyone lying to him about anything) or he's using it as an excuse because he'd decided he wanted to split up anyway. Ask him outright if it's one of these things. Hopefully he gives you an honest answer, but either way, you'll have done what you can to find out and seek a solution.
Most Helpful Girl
yes, if you want him back tel him, otherwise time to work on moving on with your life.