She wants to marry me, but...

I am a 27-year old guy and have been madly in love with a girl since we were in school together. We have never dated, and she knows how I feel about her, but she has never had more than a casual conversation with me. I know she has never dated anyone because she lives in my neighbourhood, and I finally decided to ask her out a few days ago. I got her number from a common friend and called, and she said she would meet me for coffee. When we met, she said her parents had arranged to marry her to a family friend and that she was unhappy with their decision. She asked if I would agree to marry her so she could get out of this situation, but also told me that she had no feelings for me either. I am tempted to agree because I love her so much, but don’t know if this is the right decision. Are we being hasty? What should I do?
How is this marriage of convenience good for either of you? She doesn’t love you, and you want to commit yourself to someone who admits to having no feelings so she can get out of another loveless marriage? Marriage is a commitment, not a matter of convenience, at least not if either of you are looking for companionship and love. What happens a few years down the line? You don’t even know this person and have only had one serious conversation with her in your life. Are you going to base a decision that affects you both permanently on the basis of that single chat? If she is willing to do this, what does it say about how she makes her own life decisions?

Should I tell my best friend how I really feel about her boyfriend even though I know she will probably stop speaking to me?
Why will she stop speaking to you for being honest? Isn’t that one of the foundations of any strong friendship?