Dogs can play poker, but cats put a bad groove down on Guitar Hero!

How do you tell the difference between love-struck, in love, obsession and just liking?

Please tell me that's physical therapy and not something else.

^^^ Well you have many synonyms in there and there is really no difference between them.

Love=the bond between you and this person the carefree terminology used between you two, knowing that your safe secure and that they will be there for you. Envisioning the future, making plans for future events in your head on things you will enjoy doing together, doing anything to make them smile, being sad when their sad, etc.

obsession liking etc =sex craved mischievous thoughts, always thinking about their physical attributes smile, legs, ****, etc. There may be other synonyms taken from the love definition but it is usually best described as when something is taken away that you enjoy most about the other this leads to anger, frustration, shyness, etc. Whether it's talking on the phone, having sex, kissing, cuddling, etc. Whereas in love if something was afoot you wouldn't notice it right away and it wouldn't be such a big deal. It may bother you but you won't confront it immediately whereas in obsession and your obsession is with her going down on you and all of sudden you get her to climax and she doesn't finish you off. So you will pretend like it didn't bother you but it did and you know it did and your gonna think about that all night long.