When you lose a spouse, you also lose your lover. It is normal to have sexual thoughts about your husband or wife. However, if the thoughts become compulsive or perverse, then you may have a spirit of sexual perversion. God wants to be first in your mind.
Some people may have the desire to marry again to fill a need for companionship.
Paul says, “But I say to the unmarried and to the widows: It is good for them if they remain even as I am; but if they cannot exercise self-control, let them marry. For it is better to marry than to burn with passion.” 1 Corinthians 7:8-9