Hi Nova,
How sure are you that those full body pictures of him on Facebook aren’t old? Are you certain that those pictures are reflective of how he looks in present day?
Since meeting him on the dating app, you have built up quite a good connection with him, which makes it that much more imperative that you meet him on an actual date to be sure.
The last thing you want is to lose a good connection with someone who had romantic potential, based on full body pictures of them on their Facebook account that you aren’t entirely sure are recent.
If you still feel that you just don’t want to see him anymore based on those Facebook pictures, the easiest way to let him know that you would just like to be friends is to tell him as such.
Guys respond a lot better to you when you are honest with them than if you tried to be ambiguous with your words. Just let him know that you would only like to get to know him as a friend.
If he asks why, don’t get into it by trying to explain yourself. Just tell him that you feel that a friendship just works better for you, but you understand that he might want more and you wouldn’t take it personally if he chose to move on and not pursue said relationship.
That’s really it.
The more straightforward your message is, the easier it is for him to understand it and not try too hard to encourage you to pursue something romantic with him.