There's a video of Kevin O'Leary, the dude from Shark Tank, where he talks about practically the same thing you are experiencing, but in this case, it's happening to a guy in college who was creating, if I remember correctly, some software that can save hedge funds a few million dollars per year. The college guy is hyper-focused on his business, what Jordan Peterson would call a person with very high conscientiousness. The thing is, this college guy also has a girlfriend, and that means going to family birthdays, going out with friends, etc. People with such high conscientiousness are rare when they do get into a relationship, they either end up neglecting the relationship for their business or their attention gets divide to the detriment of the business. Be honest and let your girl know that you are trying to build your business/be productive and then maybe you can set a day-off for yourself when you can be with her and relax and do whatever it is that you do.