I am currently in a LTR of 1 and half year. Currently my gf is planning her trip to vegas for her 21st birthday (i will still be 20 by that time) and since i am not 21 i won't be able to go. All of her friends are encouraging her to go and get drunk, have the best time of their lives (seen this in their texts). Is it wrong of me to get jealous?

Sorry for format i am on mobile