he initiated it, why does he now seem uninterested?

This guy started talking to me online, we had mutual friends who we are both close with so I started speaking to him. So we got talking more and he was lovely, and was initiating conversation ect and he asked me out for a coffee and lunch so I met up with him, he paid and it was good. After this we continued to text and it was okay at first, but now I'm worried he's getting bored of me and he doesn;t want to see me again. I'm concerned that I was texting him too much (I replied v quickly a lot of the time) so now when I've asked him to meet up again he's come out with excuses twice and he stopped initiating conversations over text like he did before we met up properly even though he does always reply. I am unsure why he has seemed to have lost interest so fast? Should I leave him for now or ask him what's wrong?

Sounds exactly what happened to me. Met a guy online, he was hammering my phone with messages, so I was polite and responded back. We met, had a decent date, had a good kissing session thereafter, and then he expressed an interest in meeting again via text when he got home, which is fine. The constant messaging continued until a week after we meet he literally just went quiet. However I made a point of not chasing as I didn't want to appear needy, or desperate, so I left it until Christmas Eve. I sent a polite text saying Merry xmas and HNY to which he responded with the same, said he's been mega busy and expressed that he wished to meet up again hopefully in the new year.

So I have left the ball in his court - if he decides to take it further, it's up to him . . I am hoping he does want to meet again as I do really like the guy. But who knows . . .

Leave it be for now OP, and see what happens . . .