Why do women overlook my kindness but quickly like someone else?

I have been in one sided love too many times, and if I tell them, they leave or put me through guilt trip.
The most recent example , I fell in love with my flatmate we both were master students, shared a flat for a year.
used to cook for eachother, do 90% travelling together, and spend most time together.
I fell but she didn't.
On the other hand I went out with this girl,
And she instantly liked me, and now I am in relationship in 2 dates.
How?
Looks matter that much to women?
Really?
Why do women overlook my kindness but quickly like someone else?
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