Sometimes a self-imposed break is a good thing. While you are used to spending a lot of time with a guy, a trip or busy period at work forces you to spend some time apart. Hopefully with this, he will realize how boring life is without you and the nights at home or out on the town are just not quite as fun without you by his side. He'll quickly understand that his bed isn't as cozy and he'll miss the daily chats.
Unfortunately though, sometimes by not being there and being top of mind, you're risking that he'll forget you. Maybe you have only been together a short while so life just returns to normal as you step on the plane. Maybe there are other girls in his life that seem attractive now that you're not front and centre.
If things are meant to be and you have a strong connection, even if it's early on in the relationship, an absence can make things stronger between you.
I know that I should not have to force myself into someone's life or continually fight for his attention, so I will keep going on trips and spending time apart from whoever I'm dating. If this proves to be an "out of sight, out of mind" situation, then I obviously wasn't that important to him in the first place.