Despite your rather, ahem, curt inquiry, I’ll assume you are asking in earnest.
Loosely speaking, texting chemistry is a good rapport with someone via text.
When I speak of texting chemistry in terms of online dating, it means that the other person and I, despite never having met before, have an easy, natural vibe when we text. We’re flirty, laugh easily, and/or seem to get each other.
Upon reflection, there is certainly bad texting chemistry, too. Examples include having someone misunderstand me, attack me, bore me, get defensive, write things (or send photos) that make me uncomfortable, or we simply have little in common.
(And, to be clear, that goes both ways. I’ve certainly bored other guys, failed to be sexually explicit enough for them, or been less than in some other way via text.)
I’ve had amazing texting chemistry with guys that did not translate into any chemistry in person.
Thank you for reading.