Tell her you're going to Spain on a business trip. Make it for a weekend so she'll be sure to suspect it's not really business. Tell her the trip might last longer if things work out. Tell her she won't be able reach you because it's in a secret location, but then "accidentally" give enough hints so she can figure out what hotel you'll be in. Say you'll be with someone named Mario but keep saying Maria by mistake. Then let her surprise you by showing up in your room to find out what's going on!