Spirit Love

"For God is my witness, whom I serve with my spirit in the Gospel of his Son, that without ceasing I make mention of you always in my prayers" Romans 1:9.
Whom I serve with my spirit (not the mind) is something the believer should make note of and needs to learn what this means.

After the believer is born again they have a nature to nature relationship with God through the "Christ in you" nature birthed in them.
The believer may not know this or use this nature to nature relationship but it is there nonetheless because of the birthing.
Love, joy, long-suffering, peace, gentleness, goodness, faith, meekness, temperance, truth, as well as many other characteristics can function in the spirit realm of the believer rather than in the mind area only.
It is possible therefore, that love can function in both the soul -mind and the spirit-nature of the born-again believer.
Only can it function in both places in the born-again. Because it is an attribute of God or the Christ nature the believer now has.

This constitutes compatibility between the soul mind and the spirit nature of born-again believers.
Love can also function in the soul-mind of those that are not born again. This is a love that functions according to the methods dictated by the mind it is totally subject to instability to say the least.
Spirit love functions as one of the components of the "fruit of the Spirit" Galatians 5:22, wherein is total stability because itis found in the realm of grace through the Christ in you nature.
There are no changeable qualities within the realm of Grace the more the believer learns about the grace of our Father the more stable the believer will become.