The First Love of God's children is perfectly defined in Scripture
so - rather than provide my words -- I would recommend
that those really interested in the meaning - to carefully and prayerfully look to
the Word of God only for guidance on this .
I will offer places in Scripture that were helpful
to me on this : Deuteronomy 7:6-9 , Luke 14:26 , Ephesians 4:1-6, Revelation Chapter 2