Relationship definition?

I doubt, what are the differences between below:
1) Friendship
2) Good friend vs best friend
3) bf/gf vs partner vs fuck mate (which is in trend)

I guess....
1) Friendship, are the friend that you value so much, which you think the friends worth to be friends, they would not betray you, they are always with you if you were reasonable. True friends would be always with you without making unnecessary problems to you.

2) Good friend vs best friend.
Good friends can be many, best friends just need to be 1 or 2. You only meet good friends once a while, but you meet best friends very often or you communicate with them very often. You will miss your best friends whenever you don't see them.

3) bf/gf vs partner
To be franked, I don't see the different between these two.
I see partner has better communication, as they might have some deal to keep the relationship. It doesn't need to be affair, but it can be something like soul mate. Both with some "love" to develop the relationship.

Fuck mate. Fuck mate can be partner, but they can't be bf/gf, because there is no commitment at all. However, bf/gf that have sexual activities, but do not wanna commit, it's rather more towards fuck mate. Fuck mate is with almost zero of love in the relationship, or it could be one-way relationship.

**Fuck mate is not a new term, I heard of it 3 years ago. A friend defined it to me. **

Something interesting that I heard, partner, and fuck mate could turn back as friend, but bf/gf can hardly turn back to friend once break up. Why? Too much expectation? Too much disappointment?

Sometimes I found soul mate is better. You don't have the expectation on him/her, you find him/her when you need to talk. Though it's something like best friends, but soul mate is something that more than best friends, yet will not be best friend forever.

It's so complicated, yet, this is life.

Once in a relationship, is that mean you possess him/her forever? Who knows...
It doesn't mean that you already have someone always there, at home.
If you do not maintain the relationship, you can't expect to have the same outcome as the beginning.

*** The above is the author thought, and what she heard, it is not from any of the research***