The differences of opinion between the two of you have become more and more apparent and tricky to deal with over time. There has been some struggle, silent or stated, over how serious or superficial you two really are. How firm are your values, your morals, your political or spiritual or philosophical beliefs?
All those questions and more are put to the test in this relationship. You might end up feeling like your lover challenges you on a deep level, and you could respond by overdoing it -- overstating your beliefs, for example, or how serious a subject is to you. You just can't take the same position as your lover 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 you to try to prove your point in an overblown or just unnecessary way. You could learn from this person, if you try to show them that you respect your differences; but this is easier said than done. This relationship holds possibilities of expanding your mental horizons through exposure to all the new ideas and unique philosophies that your lover brings 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. Agreeing to disagree will be crucial, and striving to demonstrate your respect for each other will help.