Out of boredom, I decided to try and find every ending in Memory Days Sim Date by Pacthesis: [link]
It took me several hours, but here is what I've found. Feel free to add any additional information in the comments section and I will add it in. If you have any questions about the guide, also direct them into the comments section below.

Endings:
1. Your Next Phone Call – End the game with Haru (don't go out on your birthday, start going out on Valentine 's Day, skip week one, don't spend Christmas with him, and don't go on dates. That's what I did.)
2. Happily Ever After – End the game with Haru (do everything)
3. All the time in the world – End the game with Daichi (don't go out on your birthday, start going out on Valentine 's Day, don't go to the movies with him, don't watch him play basketball, don't spend Christmas with him, and don't date. That's what I did.)
4. It's a Promise – End the game with Daichi (do everything)
5. Until our Paths Cross Again – End the game with Kai, tell him to leave
6. Always by my Side – End the game with Kai, tell him to stay
7. The Fallen Prince – Get the key and skip to the end (key – lake- on a tree trunk, right side of the screen (it shines))
8. Three Evil Exes – break up with all guys (tell them it isn't working)
9. Queen of the Friend Zone – Deny everyone when they ask you out or break up with them and remain friends, though this way takes longer
10. Forever Alone – Date no one (skipping everything is fastest)

Cheats:
shutupandtakemymoney – infinite money
dontneeddrugstohavefun – infinite mood
thethuglifechoseme – infinite energy
awwwyeeeaaa – unlocks all buyable room décor
 

Kai:
        
1st season Tuesday – classroom – go for lunch
1st season Wednesday – library – study for English test
2nd season Monday – hallway – work on project
2nd season Tuesday – mall – Christmas shopping
2nd season Saturday (Christmas) – library (Can date from this point) (Can only meet with one person)
(if dating) 3rd season Tuesday – lake – meet someone ^-^
3rd season Tuesday – hallway – birthday
3rd season Wednesday - cafe - go for ice cream (Can date from this point)
3rd season Thursday – library – Valentine's Day (Can date from this point)
4th season Tuesday – café – dresses as Saki
(if dating) 4th season Thursday – movies – takes you out

Haru:
        
1st season Monday – classroom – attend class
1st season Tuesday – hallway – glasses scene
2nd season Monday – library – look for book
(if good friends) 2nd season Tuesday – café – meet someone
2nd season Wednesday – classroom – birthday
2nd season Saturday (Christmas) – lake (Can date from this point) (Can only meet with one person)
3rd season Tuesday – library – study for science test
3rd season Thursday – classroom – Valentine's Day (can date from this point)
3rd season Friday – lake – hang out (Can date from this point)
4th season Wednesday – café – eat lunch
(if dating) 4th season Thursday – park – takes you out

Daichi:
         1st season Thursday – hallway – birthday
1st season Friday – park – talk about breakup with his gf
2nd season Sunday – movies – watch a movie
2nd season Tuesday – library – study for math test
2nd season Saturday (Christmas) – park (Can only meet with one person)
3rd season Sunday – mall - go to park
3rd season Monday – hallway – go to basketball game (Can date from this point)
3rd season Thursday – hallway – Valentine's Day (Can date from this point)
(if dating) 4th season Wednesday – movies – meet someone >_<
(if dating) 4th season Thursday – lake – takes you out
4th season Friday – mall – hang out

Work bonuses/days not to work there (this part isn't as complete or as accurate because I had to go through it without any cheats to see what each day did):

Café:
        Don't: 1st season Wednesday – spend more energy
Don't: 1st season Thursday – spend more energy
Do: 1st season Saturday – earn more money
Do: 2nd season Sunday – earn more money
Don't: 2nd season Thursday – spend more energy
Do: 2nd season Friday – earn more money
Do: 3rd season Wednesday – earn more money
Don't: 3rd season Thursday – spend more energy
Don't: 3rd season Friday – spend more energy
Don't: 3rd season Saturday – spend more energy
Do: 4th season Wednesday – earn more money
Don't: 4th season Thursday – spend more energy

Mall:
Do: 1st season Wednesday – spend less energy and mood
Do: 1st season Thursday – spend less energy and mood
Don't: 2nd season Tuesday – spend more mood
Don't: 2nd season Wednesday – spend more mood
Don't: 2nd season Thursday – spend more mood
Don't: 2nd season Friday – spend more mood
Do: 3rd season Sunday – spend less energy and mood
Do: 3rd season Monday – spend less energy and mood
Don't: 3rd season Wednesday – spend more mood
Don't: 3rd season Thursday – spend more mood
Do: 4th season Monday – spend less energy and mood
Don't: 4th season Tuesday – spend more mood
Don't: 4th season Wednesday – spend more mood
Don't: 4th season Thursday – spend more mood

Movies:
        
Do: 2nd season Sunday – don't use energy
Do: 2nd season Saturday – don't use energy
Do: 3rd season Sunday – don't use energy
Do: 3rd season Monday – don't use energy
Do: 4th season Thursday – don't use energy
Don't: 4th season Friday – spend more energy and mood (if energy/mood is ½ full or less)
Don't: 4th season Saturday – spend more energy and mood (if energy/mood is ½ full or less)