It happens to everyone. You find someone with whom you share one or two areas of interest. After a while, you begin to notice that other areas that interest you do not seem to interest the other person.
If your time together is limited, and especially if it is only in a time and place dedicated to the pursuit which you share, the best thing to do is focus primarily on those shared areas during your "together time". If the relationship spreads into your general interest time, then it is time to be yourself.
Recently, one of the blogs that I regularly read had some comments to the effect of "stick to the subject". I realize that I tend to discard—stop reading—most monothematic blogs after a few months. The reason is that people are not flat, one-dimensional beings. People are dynamic and contradictory. That is what makes people interesting. The chocolate fiend who will not touch dark chocolate, or the guy who will eat anything that does not eat him first, as long as it is not pizza; when you meet these people, you cannot take your eyes off of them. They are absolutely fascinating because of their contrasts and contradictions.
On the other hand, the guy who plays the same tune that he played last year and the year before will eventually become someone you avoid, the guy you pretend you did not see and rush off in a different direction in order to avoid contacting him.
Do not constrain yourself to meet someone else's expectations. Once you start doing that, you are on the way to losing your identity, becoming merely someone else's plaything. Do not be surprised at the breadth of content that you find here or on other blogs you read. Instead, look at it as a chance to understand the person behind the blog.