Regularly it's not supposed to. They are your siblings and they are important but when you get married, new responsibilities come up. You have a job, you'll have kids and you'll have bills to pay. It's easy to get wrapped up in all of it and most people do and eventually they don't have time for their siblings anymore. It doesn't mean they don't love each other. It just means they are responsible to much more that each other at that point. But every once in a while a call or a visit would be appreciated and when your siblings are in need, never fail to help them. Because they'd do the same for you in a heart beat