I don’t know that someone’s leaving the Church, whether a priest or a layman, is something to be glad about, and we should certainly pray for this priest and everyone in his situation. I would say however that I am not completely opposed to the idea of allowing married men to become priests in a somewhat limited capacity. When this topic comes up I usually say that the ideal candidate, in my non-expert opinion, would be a man who has served at least 5-10 years as a deacon, has permission from his wife, is financially stable either through suitable employment (his, his wife’s or a combination) or some other moral means, and who preferably already has an advanced degree in theology or a related discipline from a recognized Catholic college or university in good standing. It would also be helpful if his children were all grown and self-sufficient, but I personally wouldn’t make this an absolute requirement.
Such men, in my imagined scenario, would be able to go through a somewhat abbreviated formation and training program that would not significantly disrupt their family lives, given their education and experience. They would serve their dioceses by being available to offer at least one Mass on Sundays and holy days, and by hearing confessions for a few hours a week. They would also of course be able to celebrate other sacraments according to the desire of their bishop and their own availability, but would not be eligible to serve as pastors or be consecrated bishops.
This would not serve as an absolute cure for the shortage of priests, and I don’t believe that it would have prevented the above scenario (I think that not only leaving the priesthood, but the Church, is an indication that marriage was not this priest’s only issue with Catholicism), but it might be worth a try when the Church is ready.