How to say sorry after a stupid argument?

My boyfriend and I argued about something stupid. And we ended up not talking to each other for 5 days, now nobody wants to give in and call the other, bu the argument ended in a way that it is both our faults. What should I do, call him and pretend nothing has happed since we argued about something stupid?
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Thank you for the answers, OK so I will tell you why we argued to get you guys into it. I came back form my trip, and he was going to travel the next day before seeing me,(this was all done with text messages) I told him to cancel, he said he might if I can convince him well, then he started saying he likes me and wants to try new things with me, and he said he thinks I don't like him, but I should be opened to it.
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+1 y
Then I said I wanted to see him and not my friend that day and that was enough proof that I liked him, I said that if it wasn't enough then he SHOULD travel.

Then he replied a simple: "ok" and we never spoke again... since this OK on Saturday.

But thing is, he didn't travel, he only travelled the next day. he posted it on Facebook
How to say sorry after a stupid argument?
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