So recently I fell for this boy, and I want to tell him I love him. The only problem I have is that he said he’s into flat women, of which I am not. I don’t know how to tell him I like him. I know that he’s only into flat women and I don’t fit that criteria. Should I just tell him I like him? Should I just stay quiet and hope he finds someone who is flat? Please help.

What do you mean by flat? Like skinny?

I’m skinny, but he’s after a flat chested girl. I am not flat chested.

If he liked someone enough, I'm pretty sure he'd get over the whole flat-chest thing. Though, the fact that he talks like flat chests are a must-have makes it seem like he might be more interested in a physical rather than emotional relationship? Honestly it all depends whether it's a deal breaker or whether it's a preference for him. In the latter case, I'd say it's better to tell him just in case things might still work out.

If I were in your situation, I would let my feelings be known for two reasons. One, by not telling them you will always look back and regret the chances you didn't take, and two, there is always the chance that flat-chested women is just a preference and not a requirement. If it is a requirement, then they are the one that isn't worth your love, and you can continue on being friends.

1.Tell him you like him, that's obvious, seriosly IDK why people even make these threads

2.Start wearing a binder in public, it's not a total fix but it can be hepful

3.If he really likes you, he can get over your boobs anyway.

I don't have much advice to give but as a trans guy... please don't do what >>6 said and wear a binder for that reason. Binders aren't just for trans people and plenty of cis people wear them too, but to pretend to be flat for some guy you'll probably get over in a few months is not a good idea.
Binders, while the safest current option to appear flat without surgery, is still very risky and can cause permanent damage if you're not careful. From your wording, you probably have a large chest, so your risk is even higher than mine.
That said, I do agree with points 1 & 3 that >>6 made.

Just speak up, I prefer flat chests but my GF of 12 months has the largest I've ever seen, relationships are about personality not appearance,