Although I can't necessarily give you advice, I can tell you that I am going through a very similar situation right now - working full time on a start-up and live with my girlfriend. I am also 25. Sometimes, it is real hard balancing a relationship and start-up life but I have been able to do it because, although she technically does not understand what I'm doing, she knows what I'm going through right now and she is willing to make some sacrifices as long as I am. She gives me the time I need and even gives me money when I really need it (I joke around that she is my investor... lol). I have explained to her the start-up culture and she has accepted it and we are doing great now. If anything, I would try to just explain to her that you are accomplishing your goals and dreams and that you would love for her to be a part of your life but sometimes it may be hard. Email me if you want to chat about it - eintnohick@gmail.com