This is a good question, but comparing wedding vows to ordination promises is a bit like comparing apples and oranges.
First, keep in mind, one can obtain a civil divorce (and still be married in the eyes of the Church) but for a serious reason (e.g. spousal abuse) not live together anymore. Such a person can still receive Communion because they are not in an objective state of mortal sin, unlike a divorced person who remarries outside the Church who is in an objectively adulterous state because he/she is, in the eyes of the Church, engaged in a conjugal relationship with one other than his/her spouse.
For the ordained, only religious take vows. Diocesan clergy make public promises, which the Church, given the power by Christ to bind and loose, can later dispense. Therefore, a priest may apply to be dispensed from the obligations of celibacy, prayer, and obedience, but will never loose the essential character of the priesthood. He loses only his legal freedom to exercise his priesthood, but remains in good standing with the Church. The only way a laicized priest would be in a situation like a divorced-and-remarried person would be if a priest abandoned his ministry and married civilly. Such an attempted marriage would be invalid according to Canon Law, and he would be living in an objective state of mortal sin.