All praise is due to Allah, and peace and blessings be upon the Messenger of Allah.
A person's belief in Allah, acknowledgment of His blessings, and praise of Him are all signs that the foundation of love for Allah already exists in the heart, even if one does not always experience intense feelings of longing or deep emotion.
The love of Allah is not merely a passing emotion. Rather, it is reflected in honoring Him, thanking Him, obeying Him, rejoicing in His remembrance, and hating disobedience to Him.
Among the greatest means of strengthening love for Allah are:
Among the beneficial supplications is:
"O Allah, I ask You for Your love, the love of those who love You, and the love of every deed that brings me closer to Your love."
No.
A believer may love his Lord while being distracted by worldly concerns or heedlessness, causing the effects of that love to weaken without disappearing.
The more a person remembers Allah, obeys Him, and reflects upon His blessings, the stronger that love becomes, and the sweetness of faith is experienced.
Allah says:
"But those who believe are stronger in their love for Allah."
(Qur'an 2:165)
And He says:
"Indeed, it is by the remembrance of Allah that hearts find peace."
(Qur'an 13:28)
Love for Allah exists in the heart of every believer, but it increases and decreases. It grows through reflecting on the Qur'an, remembering Allah's blessings, maintaining prayer and remembrance, increasing voluntary acts of worship, avoiding sins, and asking Allah to grant His love and the sweetness of faith.
And Allah knows best.