Short answer
Spouses can maintain affection and romance through lawful expressions of love, thoughtful gestures, private time, kind words and companionship.
Islamic Guidance
What Islam teaches
Islam permits affection between married spouses and encourages tranquility, affection and mercy within marriage. Marital privacy should also be respected.
Practical Guidance
What you can consider
Continue expressing appreciation, plan appropriate private time and keep affectionate aspects of marriage private rather than displaying them publicly.
Sources
Qur'an 30:21; Qur'an 2:187.