You want to be yourselves in this relationship, and go about your life in the way you're used to or the way you see fit; but somehow, your work gets in the way of your lover's ability to be completely and uniquely themselves. Maybe you have a career that requires you to travel a lot, or to wine and dine clients while your lover is left at home, lonely and wishing you were there. This is the type of conflict that the two of you encounter as a couple, but the tension of the situation might not become apparent or really much of a problem until well into the relationship, when your individual needs become more important.
Then it starts to come out. You actually might place more importance on your career than on your romantic relationship, and for you, that is okay -- it's a choice you've made on purpose and with a clear head. But for your partner, it could be heartbreaking! Some sensitivity is needed. If you are in this for the long-term, you both have to make adjustments in what you expect from each other. Finding some middle ground is necessary. Don't try to work together, by the way; you both find that it's more trouble than it's worth, when one of you has methods or intentions that go against the other's goals. Keeping things romantic between you takes some work and planning on both your parts.