I think one of the reasons why conventional marriages last long is because of the social pressure to keep on going and the arrival of kids. Specially in countries like sri lanka getting a divorce is a social taboo. If the female party is financially dependent on husband, she is more likely to stick with the marriage even-though she wanted to go out of it. So even there is a discontent exist between married couple, they keep it going to make their families and society happy.
The arrival of kids also put additional pressure to keep the marriage going. You will hear stories that parents (specially from mothers side) lived together just so that kids have a better future. Though i personally don't agree with this assumption, i can see where it is coming from. Our socially puts huge amount of pressure to keep this 'Institution of Marriage' going. It build more pressure with the arrival of kids since it creates an additional responsibility for the parents to stick together to raise the kids. No one wants to ask the question if parents are happy or still have feelings for each other.
If everyone that are married is to have their free will exercised, it would be interesting to see how many of them would stick with their marriage. Once i asked my mother if she would have stayed with my father if i were not born. She didn't answer my question, but i saw it her eyes. Please note i am no way suggesting that all who reads this article would have the same experience. All i am trying to say here is that what you see in conventional marriages is not necessarily the reality. For that reason it is not fair to use the conventional 'marriage model' to evaluate the relationships between same gender.
When it comes to relationships, be that gay, straight or otherwise, there is very little to differentiate each other. Essentially they are same as it involves two human beings and their feelings. The concept of marriage is a social construct that was designed to keep the social order (at the expense of happiness of the parties to the marriage). Its too bad gays also want to get into this trap called marriage just to prove a point. Just because you can get married does not make you any special than the other couple that choose not to. What truly important is how happy and content you are within your relationship.
You live with someone you love as long as you feel for that person. Why do you need socials conventions like marriage to give your feelings a 'recognition'?
Do you think being with someone because that is what the society expects from you, makes you happy? I bet you might be able to make others happy by being in a nasty relationship..
Like any other relationship, some gay relationships last longer than others. I don't have statistical evidence but empirical evidence to prove this. That means, look around and you'd see what i am saying is true. If it not because of of the social pressure, conventional relationships (bind by the marriage) would also have the same ratio of success or failure as in a gay relationships. If married heterosexual couples have the same freedom as gay couples to end their union, i think we would see very similar lifespan on each type of relations.
There is nothing unique between the two (gay and straight) types of relations because both of them involve humans and human feelings. Its just that society over thousands of years has taught us to view them in a different viewpoint. We all have free will and basic intelligence which is enough for us to see through this misconception.
I like those who read this to comment on what i have just said. You may comment in Sinhala if that makes you comfortable.