TL:DR - Live with her as a roommate for a year first to soften her up, AND/OR date somebody else for a bit to provoke jealousy.

Going into my last year of college, a female friend and I both really needed somewhere to live. So we decided to split a two-bedroom apartment: she and one of her female friends (I had never met) sharing one room, and myself and another male friend sharing the other.

Very quickly, me and my female friend's roommate ("Sarah") hit it off, to the extent that my original female friend got pissed at both of us for becoming better friends with each other than we were with her. This is partially because it was a lot harder for me, an introvert, to avoid conversation with her, a roommate, the way I often did with others at my university - she loved to talk to me, for whatever reason, and I didn't have anywhere to escape to, so I was forced to talk back. Still, I never considered asking Sarah out - she was clearly out of my league, and besides, we lived together, what if something went wrong?

After over a year, Sarah moved out, to a new apartment closer to the university. It was then that I realized I liked her. Fuck. So I summoned to courage to ask her out. She insta-rejected me (ouch), later apologizing and saying she wanted to remain good friends. Somehow, this worked, and for the next six months we remained very close buddies (as I tried to bury my still-existing feelings).

I finally decided the best way to bury them would be to date somebody else - or, in my more mischievous thoughts, this would be the best way to inspire some jealousy in Sarah. So I started dating a friend-of-a-friend who lived in my apartment building. This went on for a few weeks, and I noticed Sarah starting to talk to me and look at me slightly differently. She started making somewhat rude comments about my new girl and started complimenting my appearance at a drastically higher frequency. She got defensive when I mentioned these things. Finally, one night, she marched up to me as we were leaving a party and the following exchange occurred:

"Teapot, I don't like that girl you're going out with. You could do way better. You could date me, for example."

"...Sarah, would you like to go out with me?"

"Yes, you idiot!" Then she walked away into the night.

The next day, I let the other girl down easy (she took it like a champ, we're still friend). Sarah and I have been together for the last 2.5 years.