Tell them that you are grateful that they took the time to show up on the first date, but unfortunately, you didn’t feel a romantic connection with them.
A straightforward approach is the most respectful approach.
You don’t do this person any favors by adopting an indirect or ambiguous approach.
This is where well-meaning people get themselves into trouble.
They are so worried about being honest about how they truly feel, they give the person the impression that they are interested in going on another date with them.
The person continues to communicate with the belief that another date is imminent.
The well-meaning person finds excuses until they simply turn to ghosting.
Why let it get this far?
It was not necessary.
Clearly, as a well-meaning person, you are concerned about the possibility of stringing someone along.
You obviously had a good connection with this person when you initially met each other on the online dating site.
You were just as excited about this first date as they were.
After days or weeks of buildup, you both met.
It wasn’t what you expected.
Online dating is no stranger to first dates that never lead to a second.
You are both in familiar territory.
You don’t need to feel any sense of guilt.
There are never any guarantees that the chemistry you shared with a person on a dating site is going to transfer to a real life meeting.
There are intangibles in cyberspace that are irrevocably illuminated in a real life meeting.
The real world is not cyberspace.
Something like body language and body chemistry are a lot more palpable in real life than they are in cyberspace.
The physical location that you are both in and how that affects mood and conversation is something that differs from a cyberspace experience.
Topics that were so much fun to talk about on the dating site becoming a lot more trite and boring in a real life conversation is a very real possibility.
The person’s physical appearance not matching the exact definition of what you expected even with the advantage of having seen their online dating profile photos beforehand.
They were shorter or larger than expected or their stature just seemed different.
Their hair or eye color was off.
The intangibles of cyberspace that become a lot more palpable in real life are irrefutable.
In the end, you simply realized that it wasn’t working for you and you didn’t want to go on another date.
You can spare this person all the details. They don’t need to know about what it was that turned you off.
Keeping your message succinct and informative is the only must.
A clear message that isn’t ambiguous in any way is the most respectful way to go about this.
You worry about the person’s disappointment.
This is often where people make the mistake of avoiding straightforwardness.
You don’t owe this person anything and they owe nothing to you.
You both joined the dating site in hopes of meeting a compatible relationship partner.
It didn’t work out.
Such is life.
An online dating site provides the best opportunity for people to find their best possible match.
That match wasn’t you.
Would you be doing this person a favor if you pretended to be their best possible match?
Or, would they be better off if you were honest with them about not wanting to go on another date with them so that they turn their attention back to finding someone on the dating site who is their best match?
You know the answer to that.
The clearer you are with your message, the more respect you pay to both your time and theirs.
This was just the first date.
It’s not like you have been meeting this person on dozens of dates over the last several months, leading them on.
Their emotional investment in you right now, if any, is at a minimum.
The sooner you tell them with clarity, the quicker and easier they recover and move on.