You can love someone and not want sex with them.
That reality frightens people because it seems to force an immediate conclusion.
Either the love must be fake, or the relationship must be over.
Neither conclusion is automatically true.
Love and sexual desire overlap, but they are not the same system.
The useful work is finding out what changed.
First, define the loss
Do you no longer feel desire for your partner?
Or do you rarely feel desire at all?
Do you still find them attractive but avoid sex?