How do you reply to “The key to my heart is”?

Work with the specific thing she wrote, not the romantic idea of her heart. Curiosity about the answer lands better than a promise.

What if her answer is a joke?

Then play along and make it a little more absurd. Taking a joke answer seriously is almost as bad as ignoring it.

Because they're about a feeling she hasn't had yet. It's a first text. Keep it light and she'll bring the warmth later.

Snacks. I wrote snacks. Sometimes it's that simple and sometimes it's a joke covering for something softer, like consistency.

I like it when a guy can tell which one it is. If it's a joke, play with it. If it's real, don't turn it into a bit.

What I don't want is a guy saying he has the key. That's a line from a greeting card.

Three new girls today. Pick a prompt, send what you would really send, and see who replies and what she thought when she read it. Free, no download.

How do you reply to “The key to my heart is”?: Work with the specific thing she wrote, not the romantic idea of her heart. Curiosity about the answer lands better than a promise.
What if her answer is a joke?: Then play along and make it a little more absurd. Taking a joke answer seriously is almost as bad as ignoring it.
Why do romantic replies fail here?: Because they're about a feeling she hasn't had yet. It's a first text. Keep it light and she'll bring the warmth later.