The answer to this question can be split into two ways. My first question is: what exactly is your definition of the term love? People seem to have different definitions for this. If your own definition of the word love is based on how attractive your spouse is, then your own kind of love with your spouse is ending very soon.
I think this is quite easy to understand. We don't grow new; we age every minute, every day, which means sooner or later, what you find exciting and sexy about your spouse will lose shape, and you might even not like what you'll be seeing.
At this point, your love for such a person will start to deteriorate. You may even start cheating on her. However, if your own definition of the word 'love' is based on things that are more important than beauty, then I don't think an end is imminent for your own kind of love with your spouse. Because if beauty fades away, there are still other things to behold in your partner
It is true that love can start fading away in a relationship after a few years. This statement is true only if you base your definition of love on physical things. There are people who are in love today because they are attracted by physical things like beauty, riches, etc. The fact is all of these will also fade away with time. So, when what is attracting you to a person is fading away, then the love you have will also be fading away.
Another fact is that there seems to be a lot of sexual activities at the early stage of any relationship compared to some years after. During this period, there is an excess release of dopamine, a substance that will make you be more interested in your partner. However, when love is built on things that are beyond physical things, then you see couples getting more interested in one another even year after year.