The guy who doesn't like small tits is probably self conscious about him being the biggest tit in the room.
Flat chest / very small breasts can be an IMMENSE turn-on! Having those on a petite / very girlish body can be an extreme amount of fun and very arousing. Some of the most beautiful women I've ever seen have very small breasts / are quite flat. Check out the porn model Sapphira, or Lorena Garcia on ImageFap. NOTHING wrong with them and they're quite small to very small - but immensely sexy and almost unbearably attractive.
Implants are a thing of the past. My wife had her's removed her tits clipped down to an A. I love those little bastards.
I am more of an ass man, myself. When it comes to breasts, though, I'd actually rather a woman have a flat chest than to have giant breasts. In other words, I think there's such thing as too big (for me, at least), but not too small. I've been with women that were completely flat except for some beautiful dark pink nipples that stood big and proud when turned on. I really liked that.
I've always been a huge fan of small breasts. My wife of 40 years wore a B cup bra (when she wore a bra at all) back in the early years we were together. The last girlfriend I had before her was an A cup, practically flat- chested, for all intents and purposes. That was fine with me as, when we both got naked, I was more interested in other things. (The fact that she wanted to fuck EVERY SINGLE DAY more than made up for breast size!)
Look, boobs are fun to play with, let's be real about that. Meaty, beaty, big, and bouncy. But my goodness it doesn't define the attractiveness of a woman. It's just one of a million things. If she's fun and levelheaded then absolutely not, tiny titties would not take away any fun. I mean she'd have to have redeeming features to make her physically attractive too in order for me to want to play with her, and she probably knows how to present her best features. So rather than cleavage she might opt for a thin snug shirt and no bra. Some nipple and a hint of areola will trigger the mind to fill in some depth. And she'd go for something that shows off her lower body like thin tights and no panties to draw the eye to her buttocks and groin details. Nobody is going to be thinking your tits are too small when their brain sees nothing but a sweet mound, labia, and buttocks. We're gonna wanna get close, close, close to that! She could go with shorts that hug her shape or skirt, either showing as much leg as possible so your potential partner looks there and sparks his desire. That will be accentuated if she craftily manages to offer him an upshorts/upskirt peek at her pantiless pussy. He's definitely gonna get drawn in to her. I'll take a spunky raw sexy looking adventurous girl over a prudish timid printed girl, and flat chested wouldn't be a factor.