Invalid Marriages?

[CreepyCrawler]

I have a question and it's probably going to come out really confusing, but stay with me here:

If two couples get married in the church (not to each other), couple X and couple Y, because the girl is pregnant and they're not fully aware of how important marriage is, etc., (but it's all their first marriages, no remarriage issues here) meaning that their marriages could possibly be considered invalid if they chose to get an annulment in the future. If couple X stays together forever and couple Y gets an annulment but both of their situtations are exactly the same, would couple X also be considered to have an invalid marriage? Does invalidity only occur if someone applies for an annulment? I asked before about sacramental graces in a marriage that was annulled and the answer was that they weren't there in the first place. But if couple X has an invalid but not annulled marriage -- do they have sacramental graces or not? If so, then why not couple Y? If not, then 1. how would they know this? 2. that seems unfair. It seems like you'd only know if a marriage is valid/invalid if you get an investigation done and I am under the impression that only people who want an annulment get investigations. So you'd only ever know if you DIDN'T get sacramental graces when you got your annullment. If you didn't get an annulment but you had an invalid marriage in the church for some reason, you'd live your whole life thinking you got the graces but you didn't.

Sorry my question is so convoluted, hope you can understand it!

One more question: why don't they do investigations/training to make sure that people are able to fully participate in the sacrament of marriage BEFORE they get married? then fewer people would want/apply for annulments, right?

[Adeodatus]

Canon Law always presumes in favour of marriage, i.e. if it looks like a marriage, 'smells' like a marriage, let's assume it's a marriage.

An annulment (i.e. a declaration of nullity of a putative marriage) can proceed when there is evidence for some defect [b]at the time when the marriage vows were made[/b].

If there is such a defect, e.g. through force (abduction) or fear (the girl is pregnant and girl's father is holding a shotgun to your head), then an annulment can be granted.

But even if there is such a defect at the time of the vows, there can later be a change of heart in the couple, and they really love each other and long to be with each other in a mutual and exclusive relationship till death do them part. In this case the marriage can be 'convalidated', i.e. confirmed as valid after the event (of marriage). The technical term used is 'sanatio in radice' (a healing in the root). What this means is that the couple's marriage, which could have been annuled earlier, is now healed [b]retroactively[/b], and as far as anyone is concerned, it is considered as having been valid and sacramental [b]right from the beginning[/b], right from the root (sanatio in radice).

So for a couple who can get an annulment, it was never sacramental. For a couple who later fully commit to each other, the Church can 'convalidate' that marriage, and consider it as 'healed from the very beginning'. It will be a sacramental marriage, and treated as one from its contraction.