Is it wrong to just let someone know you like them? 10points best answer?

I can't understand why relationships have to be that complicated.. Why don't people just try to get to know each other instead of playing games and playing hard-to-get?

Recent brilliant example- At the last Christmas party my cousin met someone she liked a lot..I think he liked her too cause he told her he likes being in her company..They didn't exchange any contact numbers but she found him at facebook..She wished him ''happy new year'' and he added her and thanked for her message (she told me he seemed glad to get a message from her) She asked him how he spent his holidays and he answered without asking her back..He just wished her a nice time when she returns to her home town..So, she sent a message answering what he wrote but without asking him anything..It's been more a week and he hasn't replied back..She talks about him all the time and I don't get it.. Doesn't he like her anymore? I know him and I always thought he had big idea of himself so, I told her not to send him anything..But she thinks she should send something about his interests or stuff..In her place I just wouldn't bother myself if someone doesn't continue texting with me..My cousin says that if you really like someone you try more..Well, they live far away from each other (quite many kilometers away) but can't she just ask him online whether he would want to meet in some occasion? (like a chess tournament- they both play chess like me, only they are more serious) To me dating seems simple as that, I just hate complicated situations..however my cousin says if she let him know she likes him it would be a fail cause they have talked little to each other..Therefore, they don't really know each other..

I think I don't know many things about relationships so, I'm asking for your opinions..What should she do- to be direct like I am or to continue waiting for him to reply? x)) I'm 22, she is 24 years old..Thank you for reading my question :)