| | Re: No sexual spark for a partner, then what?
I think it is wrong to consider "divorce" a solution except in some very extreme circumstances where there is absolutely no other option (i.e. spousal abuse, domestic violence, etc.). In the situation you describe I would consider it more of a cop out than a solution. It is simply an easy way out, a way to avoid making an effort to overcome a challenge in the relationship or marriage. It most certainly cannot be considered a "moral solution".
If, as you say, there is still a lot of love and a solid relationship, then that is what is most important. Where there is love anything can be overcome. Almost all marriages have ups and downs in their sex life and it is up to the couple to make an effort to spice things up and help the relationship evolve.
Bottom line...make an effort and be creative!