Shock, Awe, and Passion.

For a full second Rainbow Dash doesn't really react, sitting there stiff as a plank and with a look of shock on her face, then she wraps her fore hooves around Applejack's head and kisses her back, and Applejack smells a familiar scent, glancing down with one eye to see that RD now has her own genitals manifested...

This kiss holds them both together for a good minute and a half before they break for air, and Rainbow speaks again.

"I guess that answers my question, but why has it taken so long for the two of us to admit what we feel for each other?" The blue coated Pegasus asks in a whisper.

"Mah Family." Applejack admits just as quietly. "Granny Smith especially would just about have a heart attack if she knew I was in love with ya Rainbow, and Applebloom would not take it very well either, nor would her friends, especially that 'Scootaloo' filly who I think has a crush on ya, not ta mention our friends and mah brother, but ah jes can't live a lie no more." Applejack swallowed and said the five words that had been graven deep in her heart for most of four years then stated her position on what to do about them. "I Love You Rainbow Dash: and now that I know you feel the same I don' give a hoot what anyone else thinks anymore, if we have ta leave Ponyville and head ta Manehattan or somethin' I'll do it, I can't live with keepin' this a secret one more solitary minute." Applejack declares at a more normal conversational volume.

"Applejack, that's very touching and all, and I do feel the same, but we shouldn't just stomp on everyone's feelings. You know I'm not one to take anything slow or use half measures but I think we should break this to everyone gently, starting with your family and then our friends. Beginning a relationship with unnecessary pain and hostility is a bad move, all the people I have talked to say so: so let's do this right and with as little hardship as we can, okay?" Rainbow Dash whispers back.