Since a Kohen is limited in their options for marrying, many older (35 years or more, possibly earlier) Kohanim have a very limited pool of marriage possibilities. This is especially true of a Kohain who becomes religious later in life, where the remaining possibilities are likely further limited by personal compatibility issues.
Regarding the issue of Agunos there are many organizations that seek to help make it possible for the woman to remarry and to aid them during the period that they can't. Are there any such organizations or support networks for older Kohanim?