Questions on Romance

Here is something J and I were talking about the other night in bed:

What is the difference between emotional, physical, and romantic relationships?

Is romance the combination of both emotional and physical attraction? Do you need both to have a romantic relationship?

Is infatuation just shallower emotional and physical attraction (largely due to simply not knowing the other person very well yet)? Is a romantic relationship a deeper emotional and physical reaction?

Does this explain why J, who identifies as straight, can have an emotionally intimate relationship with a good male friend, but does not ever feel like he has had a romantic relationship with a good male friend? Is the physical attraction and physical relationship the missing piece?

Does it explain why that several women I know like having sex with other women (the physical attraction and relationship) but don't want to experience the romantic side because they don't enjoy the emotional relationship with women?

Where does mental attraction and chemistry fit in? I have felt emotionally and physically intimate with partners, but the mental attraction is lacking, and have then generally felt a disinterest in having much of a romantic relationship with them.

What entails a "romantic relationship"? What do I want out of a romantic relationship? Do I want to go on dates with that person, cuddle with them, lay in bed with them, make breakfast with them? 

Does chemistry need to be there first before any of those other kinds of relationships are satisfying? What draws us to people, even in a platonic/non-romantic sense?

CHEMISTRY!! Gah! :D