Don't rely on 4chan to give you good advice.>Step 2
Say what you want.
Star suffers because she is too afraid to say what she wants. She encourages Jarco because she wants Marco to be happy and thinks it will make him happy be with the crush he's always had. So she doesnt talk and now she suffers.
If you rewatch the Sleepover episode, you can see Jackie go through what Marco could go through. When she is asked early on who she has a crush in, Jackie says some guy at skate camp. Later, after Marco admits his feeling, she's not sure. His feelings shifted hers. By the same token, its really quite likely that Star could have forced Marco to question his feelings for her if she had just spoken up.
Last point, in relationships, its best to fail fast than to suffer long. Speak up. Tell her what you feel. Don't be an ass about it. Don't make a big show. Just get her somewhere reasonably private and tell her. If you get shot down, bow out gracefully and go cry a bit at home. You'll feel better. If she is in to it, enjoy youre new relationship but stay friends. Dont make it weird.>Anon, who are you to give advice?>Selfcucked for 6 years on a girl because cowardice.>During that time I cucked between 3 and 5 girls that really liked me.>Now married to a woman that i didnt even know at the time and celebrating our 12th anniversary.