Because your partner is so far away, you don't want to put extra pressure on your relationship. If you do something that you know they won't like (like getting drunk on a school night and not telling them where you spent the night) then it's going to break that trust and create tension between the two of you. So you'll stay sensible instead of putting yourself in the way of temptation, besides, you'd rather spend your money on a flight to see them so you don't really see it as a sacrifice anyway. Maybe only when everyone else is drunk and you feel extremely awkward twerking on the dance floor sober.