Just because you have a crush on someone, it doesn't ensure that you'll actually get together with them. Perhaps they don't feel the same way, Real Life will change the chemistry between you or maybe you just weren't meant for each other, and that's okay.
If you have a crush on somebody, just spit it out and tell them! At best, they'll just say no and we— err, you can get on with your life. At worst, misunderstandings between you will ensue, things left unsaid will cause distress and everyone will get frustrated and jump ship all-together.