If you sense an undercurrent of resistance or struggle between you, it could be that your life paths just aren't running along the same tracks. You find that you have some very different goals, which could be a problem when you're really trying to get somewhere in your life. Especially if your relationship is a long-term commitment -- or if you live together or work together in some format -- this is a real problem.
It's really hard to find any commonality, or any way for both of you to pursue your own goals at the same time, without stepping on each other's toes or otherwise hurting each other. The tension that results is subtle, but pervasive. You both feel it, and you both wish it could be resolved, but that might be much more easily wished for than accomplished. In fact, the best possible outcome of having this aspect between you is that the differences between you actually force each of you to realize your own path in life more fully, and to follow it resolutely, despite any obstacles or opposition -- from your lover or anyone else. That tension that makes things so uncomfortable between you at times also makes you stronger as individuals, and helps you to define yourself, your life and your goals regardless of what anyone else thinks.