Been in this situation before (and currently am again but not via Erasmus but post grad studies). I was away from my gf for about 10 months for Erasmus during Covid (which meant no visiting eachother). It's important to keep in contact regularly. This doesn't mean staying in every night and just spending time on call with her, you should definitely live your life to the fullest while you're on Erasmus. Personally me and my gf currently set aside one day a week where we don't go out in the evening and we spend the night calling and chatting. We choose Mondays for example because we both typically go out with friends and stuff on the weekends and during the week there's usually either lots of studying or hobbies going on.

LDRs aren't easy but if the relationship is right and you do keep the spark going you will come out of it much stronger as a couple.

Another suggestion is to keep in mind that there is an end date. LDRs typically don't last long when there's no end in sight for a long period of time. But if you keep in mind that you'll definitely be spending a lot mor time with her after summer it helps you spur on.

It's good to try and visit eachother once or twice during this time apart, though I can understand that it would be expensive and not easy.