The differences of opinion between you become more and more apparent and tricky to deal with over time. There is some disagreement, silent or stated, over how serious or superficial your lover really is. How firm are their values, their morals, their political or spiritual or philosophical beliefs?
All those questions and more are put to the test in this relationship. They might end up feeling like you challenge them on a deep level, and they could respond by overdoing it -- overstating their beliefs, for example, or how serious a subject is to them. They just don't take the same position as you do on a lot of the bigger issues, and instead of appreciating your differences as complementary, you both view them as a threat to your own point of view. This, in turn, leads your lover to try to prove their point in an overblown or just unnecessary way. They could learn from you, if they try to show you that they respect your differences; but this is easier said than done. This relationship holds possibilities of expanding your lover's mental horizons through exposure to all the new ideas and unique philosophies that you bring to the table, but don't expect it to be easy for either of you to accept your differences. This aspect could also work in tandem with other troublesome aspects between you, making it even harder to figure out how to get along. But agreeing to disagree is crucial, and striving to demonstrate your respect for each other helps.