Time management is the key to having a successful loving relationship as well as a career. Give equal time to your relationship and your career and if you are going through a particularly busy time at work then talk to your partner and explain the situation and ask for his support at this time. Do not let one of them surpass the other.
Learn How To Prioritize
Relationship issues usually spring up when you give more attention to your career over your relationship. Even though it is not of utmost importance, you still are focused on your work. This should not be the case. You should learn how to assess and how to prioritize the situations you are in. If you think that is more necessary to give attention to your relationship then do something about it. If you think that work needs to be prioritized for now, then by all means do so. It is all about balancing and prioritizing.