I don't have a solution for this, but I have a problem with how the concept of vocation is commonly applied to the various states of life. It's even an occasion of suffering for some devout faithful, with people reproaching themselves unreasonably for "not listening" to God; thinking they should have married the prospective spouse, or joined the interesting religious order, or made some other commitment. They blame themselves for past choices and past deferrals, as if God had once sent them explicit instructions by Fedex. But He didn't and doesn't.
People would be better off to seek their state in life almost without regard to the concept of vocation, rather than to make it the center of their thoughts. Seek virtue, yes, but vocation? Vocation shows up in the results of Providence, in the past more than in the present or future: in the fact of vows taken, in the approval of the Church for a priest's ordination.
Even there, our judgment remains tentative, because human intentions can be undone: a marriage may be proved invalid, a religious profession may be dissolved, a priest's promises may be released. And what we did with good will and moral certainty becomes a sort of accident. Then what: can anything meaningful be said about vocation in those cases?
A very wise Carmelite nun (now deceased, God rest her soul!) once wrote to me while I was discerning my vocation, that God calls us to be magnanimous--to be willing to give freely of ourselves in generosity. I thought this was a good way to understand vocation. It isn't because I want to do something, or someone else wants me to, or I feel obligated or coerced, but I find, in freedom this is where God wants me, this fulfills what He created me to be. Not that there are not struggles, and doubts, and temptations. But the "rightness" as a wise contemplative Dominican Prioress who I've know for 30 years has described it, the sense that this is what I was made for.
And this is what has kept me continuing to seek God and struggle in my own vocation for some 25 years. Praise God.
I understand this writer's rejection of high pressure, high guilt vocation promotion, but I think that this post swings too far in the opposite direction. I don't think that anyone ends up at the altar for marriage or prostrate on the floor for ordination or religious profession by accident. Sure, vocation, like everything else in the spiritual life, is at God's initiative. But we must respond and cooperate to bring our vocations to fruition.
As to the last point: sin has wounded everything, including the discernment of vocation. Is that meaningful?
I do think that sometimes those of us who are single (esp. if, like me, you are in your 40s, or older) and trying to think with the Church get into a sort of state where we think that we must not be listening, or that we aren't hearing what must be there. We doubt ourselves -- maybe I'm hard of heart?
I think that sometimes what's really going on is that God is calling us to be single -- and that's okay. Sometimes it is lonely, and sometimes we look enviously at those that are married or are in religious life; but I do think there is a place in God's plan for those of us that are single. We have freedom from family responsibilities, and therefore the opportunity to use that time and freedom in ways that married folks (esp. w/children) often can't.