theoretical (and not thinking about practical problems)

dogmatic, opinionated

showing idealism; believing in, based on, the idea that perfect standards are possible (and so often impractical)

visionary

generous, unselfish, imaginative, in a way that disregards one's own welfare

idealistic

having, producing, feelings or ideas about love, adventure and excitement; a person with strong feelings and ideas about love and happiness

sentimental, idealistic

existing only in the imagination and unlikely to happen; (of a person) having grand (and often impossible)

idealized, romantic