Oh that poor, confused, ginger-headed lesbian. Vagitarians don't like sausage!
And I liked the movie for the same reasons already mentioned. Every other movie involving a gay couple would use the gay "angle" as a plot crutch, or it's there to throw in some "diversity" into the film. The same problems could have happened to a straight couple's family, and whether Julianne Moore's character ended up cheating with a guy or girl didn't weigh heavily on the plot. That person really could have been a woman and it wouldn't have had a significant effect on the point of what was happening to their family (although I suppose it was significant because she cheated with the sperm donor, and the sperm donor isn't likely to be a woman).
And if I'm wrong, and people think the gay relationship was an integral part of the plot, then the only message to take home is that "gay families" can have normal family dynamics, and have the same problems with teenage kids, trust, etc.