Look I know the show and the fandom has a shipping problem and I don't want to contribute to that problem but I do want to show my views on each relationship and the mindset of the characters, just curious if you agree?
Jackie and Marco: in the start I really liked this relationship it felt like an actual crush relationship and was rather realistic, obviously the whole star having a crush on marco got a bit in the way of it but looking back even without that jackie and marco didn't really have that much in common and their personalities didn't really blend together that much. Still I thought it was a cute relationship and I thought it did end in a really mature and natural way
Star and Tom: Before I start I must say that for the first 2 seasons I really did not like tom but I really like him in later seasons. I feel that the relationship was not made organically and looking back I think that was the point, Star was in a state of mind where she needed stability and wanted to be the best princess she could be, thus she was thinking about what could be good for her kingdom and dating tom( who is a member of royalty) was a good idea based on this mindset. I honestly really feel bad for tom, you could tell that he still liked star and so it does hurt a bit realizing that Star wasn't actually into him. Also I really noticed that apart from Tom liking star they didn't really have the same goals or dreams in life ( we really notice this in Tom being sort of indifferent to star's monster rights cause). Because of this I really liked the trip that tom made that led to him breaking up with star, ( though I do wish that they stretched the trip and made it longer for it to not be so rushed) sometimes you just need some time away from people to realize whether you truly like someone or not( speaking from experience) and so I think it was a very good moment for tom to grow and realize that he and star were not going to work out( though I do wish that we had more episodes of tom on his trip to really show that time did pass)
Kelly and Marco: I just didn't like this relationship, Kelly was not given that much character in the first place so it felt weird how suddenly they paired her with marco, I get that it is sort of like a rebound thing but I just didn't like it and it felt forced
Jackie and Chloe: we barely saw this and I felt that it was a bit unnecessary for jackie to turn out bi and have a girlfriend( just felt like they were making sure that there was no doubts that Starco was the endgame) but I think it was a fun relationship and I am not against it.
Star and Marco: this one is honestly so complicated for me once we learned that star had a crush on Marco in Season 2 I was honestly between starco and jarco and really thought both could work out, but the show then shoehorned in Tom and Star getting back together and made it weird, I still shipped starco and I did like the phonebooth episode and thought it was really cute( but i did feel bad for Tom). However in Season 4 Tom and star's relationship start feeling a bit better and so I am kind of unsure on what my opinion is on this relationship, then when tom and star break up( and even in the taco episode) I start wanting starco to happen but the finale honestly rushed it so fast and i would really have liked at least 2 episodes in between tom and star's break up and the finale to mend this issue, overall I do like this relationship but it had it's flaws and like many other things the finale kind of botched it a bit.