"But I am constant as the northern star"
Assumptions are frequently wrong. We have all known this since we were children. And yet we assume things every day. Assumptions are a matter of necessity; we don't have the time or the resources to thoroughly evaluate every question that comes to mind. So we assume based on observations of common behavior and make the best of things – and we identify incorrect assumptions as often as is possible and correct them.
One of the common assumptions we make is that other people's thoughts and feelings are relatively straightforward. Many people try to gauge the interest that another person has in them as a simple yes or no question: "is he (or she) into me?" Love is not a box to be checked. There are many aspects of love and ways in which it is manifest, each of which can be felt at varying levels of intensity at different times.
We know this because we experience it ourselves. Even without a particular cause, our feelings about people change from day to day and even from moment to moment. We love people for particular characteristics without appreciating others that they possess. Sometimes, we have have every reason to appreciate someone but we don't have romantic feelings towards him or her.
And yet it seems to puzzle us when we encounter complexity in the feelings of others.
Although the tendency is for our feelings to change, we are not prisoners to our unpredictable feelings. We have the ability to encourage or discourage feelings. Love is a choice; I can choose to work on loving people or I can choose to not do so. If I spend my time serving others, I will love them more. If I ignore them, what love I have for them will fade. This choice is especially important for the stability of our families.
As regards others' feelings, we can choose to be patient. We can remind ourselves that their actions may lead to contradictory conclusions because their feelings contradict each other – and that this is normal and understandable. And we can focus on developing and giving love more than on receiving it.