Short answer
Emotional distance can develop through unresolved conflict, poor communication, excessive work, financial stress, lack of quality time, family pressure or taking one another for granted.
Islamic Guidance
What Islam teaches
The Qur'an describes marriage through tranquility, affection and mercy, encouraging spouses to maintain a relationship of kindness.
Practical Guidance
What you can consider
Identify the specific source of distance rather than blaming the spouse generally. Rebuild communication and seek help when necessary.
Sources
Qur'an 30:21; Qur'an 4:19.