No civilization in history has ever collapsed from the lack of the (nuclear) family. Nor any other form.
Are you for real or just trolling for lulz?
I strongly disagree.
Erosion of the family unit is what kills a civilization, since the family is the building-block of society.
Using the starting premise that we are made to be sexual beings, I can see a case for the OP.
This would also assume we learn to be heterosexual as the normal and other forms of sexuality as other possible outcomes.
A concept for modern society is monogamy, a married m/f pairing producing children. This goes against our nature of being sexual beings and forces us to select a mate and stay faithful. A problem with this is jealousy, that if a person hangs out with other people the mate may become jealous and suspect infidelity. This leaves a married couple with no one either can see on their own, but each person has to be chaperoned or they must be with each other. That would cause a very isolated existence.
But if you stigmatized homosexuality, men can hang out with other men and women with other women, because there is no perceived threat to the marriage.
So hetero marriage need stigmatized homosexuality to be viable. Without a stable hetero marriage society as we know it, the structure to raise children, collapses, and without something else to take it’s place, yes the OP is possible.
If infidelity is the problem, wouldn’t a taboo against adultery be more useful then a taboo against homosexuality? And if you have a society were it’s “safe” for men to socialize with men and women to socialize with women, who do couples socialize with? You end up with both partners having to lead separate social lives - hardly a situation which fosters strong pair bonding.
What do you mean by “stigmatized?” I don’t understand how the viability of hetero marriage is in any way connected to homosexuality, stigmatized or otherwise. If I have an ignorant view, please correct me.
Family has had hundreds of variations over the centuries, and the nuclear family only exists because the wealth of the 20th century allowed new couples to move away from their parents and set up completely separate households.
Families can be the clans we’re born into, the ones we create through marriage, or the close bonding of life friends in a wider circle. What matters are that individuals are bound to one another through something strong than, say, an employer/employee relationship.
That last one was just a joke, but I’m serious about the importance of the traditional family unit. Is the part where SD wolf-packs me again?
The penalty for adultery is often death in early societies. Either by civil authority religious authority or by right of revenge of the spouse. So yes taboo also.
Together the spouses can hang out with anyone, but if they are on their own hanging out with the opposite gender is suspect.
The reason needed for stigmatizing homosexuality would allow the spouses social contacts with other people. The stigma makes it OK for men to have men friends and women to have women friends. It also divides the genders, traditionally men work together, women raise children together.
Yes the system is isolating and not ideal, but far better then a system where you could not see anyone without your spouse present. It is the cost of allowing marriage in my above proposed reason.
stigmatizing in this context: defining homosexuals as not worth considering part of the human family, a lower class of defective people.
We all need friends, but monogamy + jealousy lead to isolation. Isolation is a destructive state for humanity. By creating a system where it is safe for like genders to get together you get rid of the isolation.
Normalizing homosexuality means spouses now can’t see anyone, even if the intentions are non-sexual, so the spouses become isolated, have no friends.
Also if our natural state is that we are sexual beings, and that is only suppressed that is our learned monogamy, normalizing homosexulaity may re-ignite us as sexual beings, which may cause more infidelity.
I’m just not accepting these arguments. Even if you have a society in which there is complete acceptance of homosexuality, the majority of people are going to be heterosexual by choice. So heterosexuality will never be overwhelmed by homosexuality. The explanation of homophobia lies in people seeing a problem with a homosexual minority.
The starting premise is we are as a default a sexual expressive being, basically causal bisexual, and only learn how to restrict that from society. With that condition does that change your acceptance?
You’re not actually arguing choice in sexuality, are you? Or are you talking about choosing to participate in homosexual behaviour? Quite a distinction.
I’m not sure normalizing homosexuality (further) would do that. And what does normalizing homosexuality have to do with married people not being able to “see” anyone? Are you talking about adultery? Adultery caused by (completely) normalized homosexuality?
I think you’re conflating love with sex.
So if homosexuals (normalized) destroy hetero monogamy, seducing hetero men and women away from their spouses, civilization is doomed? Are homosexuals and their natural promiscuity the end of civilization? 
But it might be a society where many if not most persons of the “hetero” majority have had occasional homo experiences. Which would be just as bad.
Heterosexual by choice? No one is heterosexual by choice. And I’m not talking about bisexuals who choose to neglect half of their sexuality.
Nevertheless, no civilization in history has ever collapsed from the lack of the (nuclear) family. Nor any other form.
You seem pretty certain of that. What makes you so certain that the survival of the family is immaterial to the survival of civilization? I still can’t help but think you are grossly underestimating the importance of family.
I’m talking about jealousy, which is the real issue, which causes homosexual oppression.
In some types of ideal relationships I believe they are suppose to go together. Love the primary that brings along the physical sexual relationship.
Civilization as we know it. Sure another model may develop, perhaps a better one, sounds like it will be a freer society, but not everyone wants that.
What makes you think that the survival of the family is in jeopardy? And do you have any real-world examples?