Is it normal to be obsessed over someone ?

My friend is really upset because she was gonna tell him she had a crush on him but he said he was gay. She's had a crush on him for weeks. Now she still likes him and she likes him even more. She can't stop thinking of him. She cried over him the first few nights after he told her. She said he was so adorable when she was working with him she'd stare at him every night. She couldn't take her eyes off of him. She said it was love at first sight for her but she was scared to tell him. I saw her last night she was still crying over him she told me how badly she wanted to be with him she loved him so much her stomach hurt. She said they were gonna get married she even picked out names for they're kids. She told me every little thing. She said he was nice to her he hugged her every night and the first time she told him she liked him he smiled at her. She wished she told him sooner she had a crush on him but she was too scared. She said he was being sweet to her. Now she's mad and not talking to him. He said he's been trying to message her on Facebook to hang out and stuff but she's ignoring him. She'll be seeing him again in a few months she's not gonna know what to say or do then. She feels like the next time she sees him she'll have to tell him how she felt about him but she's really scared and upset she's not sure she wants to talk to him but she can't help not talking to him. He said he wasn't interested in her he only had one girl he likes but she was married. She's really mad at him and can't get over him. Is it normal for her to be obsessed with him ? She wants to know if she should talk to him about her feelings for him or should she move on ?