You can see from the screenshot Theodora practically loves me haha. Inviting her to dinner (LOL just kidding)

Factors Boost:
-1) Restoring their civilization after they were wiped out (200 points positive)
-2) Liberating the Player's Capital (80 Points Positive)
-3) Making a Public declaration of Friendship (High Value about 45 points)
-4) Having the Same ideology (45 Points Positive). Note: If you have a different ideology is very hard to become friendly and a war could ensue.
-5) Denouncing the Same Leaders
-6) Building an archeological site on their territory for them (a positive boost)
-7) Liberating their non-capital cities or their prophet/workers (a small positive boost)
-8) Voting for them to become Host World Congress
-9) We helped their proposal
-10) They liked our proposal to the World Congress
-11) Making Declaration of Friendship with the Same leaders
-12) Fighting a Common enemy (Reduces warmongering penalty with the AI). This has a decent positive value but does diminish rapidly.
-13) Shared Religion (Positive but diminishes overtime)

If you have enough Positive points they can vote for you to become host for world congress (but you need high amount like restore their civilization)

-1) Warmongering (This can be very little to extremely large): It is very hard to predict. Some Ais overlook modest warmongering, others dislike warmongers and even worse some hate warmongers. The way to reduce it is by 1) fight against a common enemy 2) Liberate a city state if you can 3) Limit your warmongering to essential targets

-2) You have declared war on your friend (-45 points diplomatic). Better to avoid this. I know sometimes the Ai trolls you and decides to convert your cities to their religion despite the fact you asked them not to.

-3) You stole their land with a Great General (This may happen if they have different ideology and they are trolling you and they steal your hand first)

-4) You have denounced a leader you made a friendship with (-35)

-5) You have chosen a different ideology (-45 not sure)

-6) You have denounced a leader they have befriended

-7) Other Civs that we like more than you have denounced you (This is very bad potentially. It means they won't side with you)

-8) They believe we are building new cities too agreesively (LOL this is when the Ai gets jealous. While this is not very high, I have seen AIs denounce me out of jealousy. It is quiet surprising)

-9) You ignored their request to (Stop bullying city states/stealing their artifact and spread your religion)

-10) You helped their proposal fail/ They do not like our proposal at World Congress

-11) You conquer their capital (-80)

-12) You denounced them or they have denounced us (either one is -35)

New: 13) You lied about not going to war and declared war (when they asked you about your troops on their border you said "we are passing through"). This has a 30 turn limit so it is not forever

New -14) @eternally reminded me to add " competing for same city states!" (minor negative modifier but with Alexander could be more perhaps)

World Congress: Make sure you pass World's Fair, International Games, Art Funding (However, this may work against you so be careful)

If there is an AI a lot of other AI's have denounced then feel free to denounce them

Do Not backstab any AIs if you can (unless they are going to win the game): Do not declare war on your friend (-45 diplomatic points)
Don't denounce an AI you made a declaration of friendship with (unless you are forced to go to war with them cause they are going to win the game. Better to denounce then declare war , the diplomatic penalty is much less).

This Point has often been Overlooked:
-If an AI was friendly with you, you signed a research agreement. Now you are no longer friendly and are possibly hostile! The Good News is they will not declare war on you until the Research agreement finishes (99.99% of time)

NQ mod is awesome and enhances game play
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2163957386