1. Schedule regular check-ins.
It seems kinda obvious, but if you can’t have dates because one of you is in Chiang Mai and the other one is in Cincinnati, you’re going to have to be proactive about scheduling time to see each other’s faces. Nothing makes someone feel important and part of your life like showing them they’re not “out of sight, out of mind.”
Build a Google calendar you can share to schedule dates, or have regular weekly or daily Skype calls. I met a girl at a magazine launch whose boyfriend was in the Peace Corps in Moldova, and she napped in late afternoon so she could get up at 3am and videochat him as he ate breakfast. That’s a little extreme, but you get the idea.