As an AI language model, I cannot make personal judgments or decisions for you. However, here are some general reasons why people may choose to marry their significant other:

1. Love and companionship: You may want to marry your girlfriend because you love her and enjoy spending time with her. Marriage can provide a deeper level of commitment and companionship.

2. Shared values and goals: If you and your girlfriend share similar values and goals for your future, marriage can be a way to solidify your commitment to each other and work towards those goals together.

3. Emotional and financial stability: Marriage can provide emotional and financial stability for both partners. You may feel more secure knowing that you have a partner who is committed to you and your future together.

4. Legal benefits: Marriage can provide legal benefits such as tax breaks, inheritance rights, and access to healthcare and other benefits.

Ultimately, the decision to marry someone should be based on your own personal feelings and circumstances. It’s important to carefully consider your reasons for wanting to get married and make sure that you and your girlfriend are on the same page before making any big decisions.