Is Remarriage a sin...many today are on their 2nd or 3rd spouse?

if u divorce because of adultery, which according to the bible is the only true reason to divorce someone, then it is a sin to remarry whether you were the one who cheated or your spouse was. i'm not sure if it's a sin to remarry after your spouse passes, but it probably is. the bible believes that marriage and sex are for two people and two people only. even after the marriage is broken, u are still "tied" to that person and therefore shouldn't be with another.