Need advice and some male perspective 🆘?

Dating awesome guy (guy A) and recently became exclusive (we have said the L word, he met my parents and whatnot). However, back in December long time best guy friend (guy B …20 years plus and our families are friends... spent holidays together growing up etc.) won an all expense paid work trip for two to Hawaii for being top sales (guy B lives in west coast , I live on east coast).
Guy B asked me to come as plus one, since there's an awards dinner and ceremony with other people from his company, pretty much a large work trip party. Of course I said yes, because who doesn't love a free first class trip with a longtime friend (and wasn't serious back in Dec. with guy A). Guy B is not dating anyone so don't think he wanted to bring another guy or his mom (lol)... and I am under the assumption this is platonic (especially since we live opposite coasts... so he is far from being a threat to Guy A and Guy B and I have always had a platonic relationship).

I mentioned to Guy A I have this trip back in January but didn't discuss it was with a Male friend (guy b ). The trip is coming up and I am scared to tell (guy A) because I don't want him to be upset and worry for no reason, even though I am going platonically. I also don't want to cancel last minute on a good friend (guy b and miss out on a fun trip with a long time friend) Any advice?
Need advice and some male perspective 🆘?
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