Either husband or wife may apply to the Family Court for a divorce in each case of the following subparagraphs: <Amended on Jan. 13, 1990>
1. If the other spouse has committed an act of unchastity;
2. If one spouse has been maliciously deserted by the other spouse;
3. If one spouse has been extremely maltreated by the other spouse or his or her lineal ascendants;
4. If one spouse's lineal ascendant has been extremely maltreated by the other spouse;
5. If the death or life of the other spouse has been unknown for three years;
6. If there exists any other serious cause for making it difficult to continue the marriage.