Will & Grace: the other "GAY marriage"

Of all the possible relationship combinations that exist in life, one that was recently popularized by a TV show and which happens more often than people would imagine is the somewhat dysfunctional Will & Grace relationship combo.

He's gay, cute, successful & single and so is she, they have been friends forever and even move in together at some point; they are for all intends and purposes a couple.
Are faghag / gay unions factual and possible in the long run? Does this bond fade when one of them finds happiness on a meaningful relationship that includes sex? It should not be the case if Love is true & the friendship strong -i.e. One is not using the other to compensate for having a crappy love life, until mr. Right comes along-

One of the things I've learned in life and which makes me frown when sectors strongly opposse gay unions is that happiness, families and bonds are like balloons... Come in all shapes and sizes but the final use is still the same

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