Here are some tags for couples massage:

#CouplesMassage
#RomanticMassage
#MassageForTwo
#CouplesSpaDay
#RelaxTogether
#IntimateMassage
#RomanticGetaway
#MassageTherapyForCouples
#CouplesRelaxation
#LoveAndMassage
#TandemMassage
#SideBySideMassage
#CouplesWellness
#SpaDayForCouples

You can also consider long-tail tags to be more specific:

#CouplesMassageForAnniversary
#RomanticMassageForCouples
#CouplesSpaDayIdeas
#MassageTherapyForCouplesStressRelief
#CouplesMassageForIntimacy
#RelaxationTechniquesForCouples