Sentence structure and meaning (parallel structure)

Question

In the first paragraph of this article about friendship, I encountered the following sentence:

Already the characteristically modern relationship, it [friendship] has in recent decades become the universal one: the form of connection in terms of which all others are understood, against which they are all measured, into which they have all dissolved.

I am struggling to understand what this sentence is trying to convey, especially the bolded part. My guess is that it means

(1) Any other people are considered friend if and only if I understand them.

(2) I always evaluate other people using friendship as the only measure. That is, I always divide all other people into two groups: friends and non-friends, and there exists no third catagory.

(3) Once someone becomes my friend, he/she is integrated(dissolve) into a large homogeneous group, namely friends, and is not treated as a separate person any more.

I am particularly not sure about the second and the third points, while not 100% sure about the first point as well. If anyone understand this sentence I will be grateful for any help.

Answer 1

The key to understanding the meaning is by reading the text following the sentence - the sentence on its own is very confusing because there's no context.
So if we read further in the article:

Romantic partners refer to each other as boyfriend and girlfriend. Spouses boast that they are each other's best friends. Parents urge their young children and beg their teenage ones to think of them as friends. Adult siblings, released from competition for parental resources that in traditional society made them anything but friends (think of Jacob and Esau), now treat one another in exactly those terms. Teachers, clergymen, and even bosses seek to mitigate and legitimate their authority by asking those they oversee to regard them as friends. We're all on a first-name basis, and when we vote for president, we ask ourselves whom we'd rather have a beer with. As the anthropologist Robert Brain has put it, we're friends with everyone now.

Romantic partners also considers as friends, spouses considers as friends, parental relationship considers as friends; and so forth through other relationships.
So as I understand the meaning it is that the the characteristics of the type "friendship" has become the norm for other types of relationships as well. Note especially the last line of the paragraph:
As the anthropologist Robert Brain has put it, we're friends with everyone now.

So using that:
The form of connection in terms of which all others are understood
We understand relationships based on the way we understand friendships.

against which they are all measured
We measure relationships in the same manner we measure friendship.

into which they have all dissolved.
This speaks to the "we're friends" line; all relationships have dissolved into friendships.