Boyfriend went out with other girls without informing me. Should I be jealous?

Hi! Saturday morning my boyfriend told me that he along with his cousin brother (xyz) would go to xxx Lake and then they'll go have lunch. I slept after this because it was around 1 am here in India (we're long distance, he currently lives in the US for his studies). When I woke up we were texting each other and then I opened Instagram and saw his cousin's story and I saw a picture of him along with my boyfriend and there were two girls too. The four of them went together but my boyfriend told me that it's just gonna be him and xyz. I was hurt obviously but didn't question my boyfriend anything related to this. After a while he himself texted me saying that he was quiet the whole time he was out with xyz because xyz had invited two of his girl friends.
We had a fight obviously.
He knows how insecure I get. He knows everything but he still went and now he's the one who's been ignoring me since the last 3 days instead of saying sorry and making up

Boyfriend went out with other girls without informing me. Should I be jealous?
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