EDIT: For those who might have the same problem as I did, coming back to this question I see why I failed back then. The question is very unspecific: What is the probability that A man and A woman (meaning any couple) happen to be married to each other. We actually don't care which one, just a couple out of those eight. My earlier approach was focusing on specific 2 people, however, couples could have been constructed from any of the other couples so zeroing in only on 2 specific subjects out of 8 is not accounting for all possibilities, as other couples could also be formed that are married to each other. So my approach of 2/8 x 1/7=1/28 was wrong as there is no sequence, we are randomly choosing this unspecified one couple. If I have to calculate it like that, to account for search for the unspecified couple, we just choose any of the 8 and then look who is left that could ACTUALLY match. So instead of 2/8 x 1/7 we count 8/8 x 1/4 because any person could be selected first and then only 4 of the left could match, either man, if we first selected a woman or a woman if we first selected a man. We are not asked what is the probability that AFTER selecting a man, his wife is selected or vice versa. If the order of selection is not specified and no sequence is provided, we can be as unspecific with our calculation as possible. That is why we don't have to add the probability that a woman is selected first and man second to the probability that a man is selected first and a woman second, like I proposed in my second question. Order is not specified, hence, we are not considering any order preferences at all. Also, adding both probabilities would only be possible if we had an either or situation, a situation with mutually exclusive events. In our case, the probability of selecting married couple 1 or 2. As we can't select different couples in the same selection we would add those probabilities together to get 1/4+ 1/4=1/2. However, selecting man or a woman first is NOT mutually exclusive as they lead to the same event: bringing together the same married couple.
However, the easiest way to solve such a problem is to count all possible cases and define what are the sought cases. Here, it is 4x4=16 and 4 married couples. 4/16=1/4.