I think it is very normal to experience grief at parting.
You might consider trying to recognize it as a testament to the strength of your desire to be TOGETHER as opposed to an obstacle.
You're both feeling it because it messes up your routines and comforts. It's a natural consequence of the lifestyle and relationship you have chosen.
Try to pivot your thinking a little here and view your visits as contained events.
Know they are temporary now, but will cease to be temporary in the future.
Express these feelings openly and discuss with your partner.
Secondarily - make plans. Make a digital date night and find activities you can do together over discord.
Livestream to each other, watch movies synchronously, play games together or apart but simultaneously. Tabletop Simulator is great for this, you could even involve mutual friends.
It sucks to be apart but there is a lot you can do to feel as close together as possible while we all wait this out.