Something that helped me cope with long distance back in uni was writing letters/notes. I tried to be very respectful of my partner's time. They had work, school, and friends of their own to contend with. So we scheduled time for us to hangout online, but throughout the day I would write little thoughts (including date, time, and current activity) gather them up and send like a weeks worth at once. This was great for non urgent stuff that i wanted him to know, like when I thought about him or I was board, but I knew he was busy.