I'm 32 year old man & have not had sex. The only sexual sin have committed is masturbation.

Ever since this particular lady moved to my neighborhood, she causing me unwanted sexual arousal all the time. I do not think or have any sexual desire or thought towards her but any time we sit together or just engaging in conversation, I immediately experience uncontrollable unwanted erection. Worst still, when we are both taking a walk together, my penis is erected with the bulge almost noticeable by anyone who look toward my trousers. I'm just ashamed as I do not know what to do. No lady has ever made me arouse like her. She is single & God fearing but I believe am older than her by one year. She even said she's a virgin but I refuse to believe. Deep down in my spirit I like her but no sexual feelings towards her. I have not told her anything but basically we are just good neighbor. If i tell her lets take a walk, she obliged even before i finish talk. What should i do please? Is this my future wife or what? I never been in a relationship all my life but I do have female friends (not girlfriends)