Well both parts that you have said are somewhat a bit exaggerated, at least in my experience.
The first year of marriage is actually the toughest. You are getting used to sharing everything with another. Don't get me wrong, it is a wonderful thing to share everything with your beloved, but it is a change that takes getting used to.
As for me and my wife, we didn't have sex everywhere, such as malls, restaurants or whatever. We confined this mostly to our own home. Sex is always great. It is great because of the love we share for one another. I have been married a bit over 3 years and sex has never gotten less passionate because our love for one another is still there. Passion comes out of love and if your love dies, passion dies, but if love stays and even increases(as it does for me and my wife in our marriage) so does the passion.
Let me tell you the key to making a marriage work. It is being a servant as Christ tells us to be. Being a servant to one another. This is the key. Too many marriages end because one or the other or both become selfish, thinking of what the other can do for them, instead of what they can do for the other. If you maintain this servant attitude, love flourishes, and out of this love comes passion, the key to the romance. With this the marriage and yes sex, will be great because both individuals are trying to please the other.
Having the servant attitude like Christ told us to have is often overlooked in Christians today. It is easy to fall into the worlds thinking of, 'what about me?' We should be thinking, 'what about you?'
Jesus said love your neighbors as you love yourself. Everyone on this earth is our neighbor. Paul teaches that if we don't love our neighbors whom we see, then how can we love God whom we don't see. He goes on to teach that if you don't love your neighbors then you surely don't love God. Having a servant attitude is loving your neighbor, which in turn shows you love God.
God Bless