This is a song about a man who has to leave his wife or girlfriend for a time. He doesn’t really want to leave her behind but he has no choice. His being able to stay is beyond his control. It could be due to a business trip, a military deployment, going on tour with his band, etc. Regardless the reason, he regrets leaving but knows its his responsibility to comply and tells her he’ll be back to be with her once again.
Husbands and wives of sailors and soldiers go through this scenario all the time. It’s heart breaking to leave their loved ones behind for months at a time. It’s not by choice but a requirement. Those left behind have to be brave and wait for the day when they will again be reunited. During war unfortunately, that time may never come.