If someone says they love you today, that might not be true tomorrow!
Feelings change!
They evolve!
This means as well that you can measure a feeling's intensity at one given time.
And you can measure it as well by how often that feeling repeats itself and for how long.
An "I love you" that you share with someone once has a certain value.
That "I love you" will have a while different depth and intensity if it is shared thousands of times over 53 years of marriage.
See the difference?
You might tend to forget about that in your conversations or your beliefs.
Your lover might have shared feelings with someone else years ago for a few days.
It doesn't mean that these feelings are alive today.
Check the continuity and repetition of an emotion when assessing its depth.
This will give you a clear indication of its real intensity.