Bruce Willis and wife Emma Heming have celebrated 12 years of marriage - and Emma has opened up by admitting it hasn't always been easy.Bruce, 65, and 42-year-old Emma wed in 2009, and have two daughters together, Mabel Ray, eight, and six-year-old Evelyn Penn.Emma shared a sweet snap of the pair kissing, and captioned it: "Boy I sure do love this guy to the moon and back!"Even though there’s been times I would have loved to take him to the moon, drop him off, and come back solo!"MORE: Demi