Should I go out with other people?

I am a 23-year old woman and have been dating a guy since we were both 17. He wants to marry me, and I am in love with him, too, but I sometimes wonder if we are thinking about this plan only because we have been together for so long. I am not worried about falling in love with someone else because he is also my best friend, but I don’t want to regret this decision when I am old and realise I have never dated anyone else. Am I missing out on something? Should I go out with a few people and then come back to him just to get this out of my system?
What exactly do you want to get out of your system? Think about why you feel the need to go out with other people, and what that accomplishes. Think about how he will feel about this idea, and the potential damage it may cause you both. If you love each other, and are best friends, you have already found something it takes most people a lifetime to find. The best thing to do is wait and watch as your relationship evolves. You are both still young, and under no pressure to marry. Talking about it is perfectly okay, because you don’t have to commit to it until you are both ready, emotionally or financially. Why not give yourselves some space to breathe, take it one day and a time, and see how you feel about this a few months from now? Why create a problem where one doesn’t exist?

My girlfriend and I have been speaking about how we don’t split our bills when we go on dates, and she believes we should start talking about it more often. I think she is too money-minded, and this kills the romance. Is she right?
Why is talking about money an indication of romance or lack of it? If she wants to be mature and talk about money, it is probably important to her.