i should mention, having God's love is enabling you to love, remember that God's love is also not a measure of your self-worth.

e.g. "please don't leave me" -
a. i have no love from God and you're my only source, so i need you. (fundamental need won't be met)
b. my self-worth is determined by outside love for me, and i also know no God. (self-worth determined by external conditions) "i'm nothing without you"
c. i have God's love and can freely give it, however my self worth is still determined by external conditions

e.g. "i have no fear of losing his/her love"
a. i have God's love, but my self-worth is determined by external conditions (sometimes a person in this situation will flipflop between feeling they NEED their significant other and then not later. humans are unable to feel God's love every single second of their lives)
b. i have no fear of losing his/her love (but i will still grieve the loss of the love and friendship, also, although it may sound ideal, humans are not perfect. Humans can work towards it, a journey of healing, approaching but never reaching.)

Having absolutely no fear of loss of love is most likely unattainable, but it is quite attainable to not fear the loss enough to let it go.