Laws of Eating Teruma
There is an interesting Halacha related to the divorced or widowed daughter of a Kohein. If she has no children when her marriage is terminated, she is permitted to go back to her father’s house, and continue eating Teruma again.
There is a case brought in Masechet Yevamot that speaks of a divorced Kohein’s daughter, who gets Halachically engaged, known as Erusin, to another Kohein.
Since this marriage is forbidden from the Torah, as a Kohein is not allowed to marry a divorced woman, her Teruma rights are terminated as soon as she is engaged.
If this potential marriage is terminated at this stage of Erusin, she may still go back to her father’s house and eat Teruma. If it is terminated after marriage takes place, and this marriage was consummated, she may never eat Teruma again.
If she was a widow married to the Kohein Hagadol, which is forbidden, and this marriage ends with the death of the High Priest, she is still a widow.
However, since she transgressed a negative Torah commandment, she becomes a Chalalah. This is the same name given to the offspring of a forbidden Kohein marriage. She can never eat Teruma, and never marry a Kohein.
We see that there was a special level of sanctity that the Kohein needed to maintain as a servant of Hashem.