What if a couple is happily married for many years and have no desire to part, and yet suspect that if they did divorce that grounds for an annulment may exist, should one be pursued?
Of course not. The Church presumes a marriage to be valid – sacramental if both parties are validly baptized – unless proven otherwise by an ecclesial marriage tribunal. If there are circumstances that exist that cause the couple to be concerned that their marriage may not be valid, they should find out if those concerns are valid, and, if so, have the marriage regularized. Once regularized, the marriage will be valid and sacramental (if both are baptized). For more information on whether or not the marriage is valid, I recommend consulting with the St. Joseph Foundation, an apostolate that specializes in canon law.