Am I being unreasonable?

The guy I love recently got reconciled with his girl bestfriend and now he was asked by the girl to accompany them to travel abroad to serve as a tour guide. He knew the girl had feelings for him, I got jealous. Something shifted since they got reconciled and it hurts me that he would spend more time with her than with me unlike before.

If you are in my situation, will it be a deal-breaker for you? Or you would just let it be? I am confused since I am kinda all in whenever I fall in love. Thank you.
Am I being unreasonable?
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