Tbh for me once tomstar was going on, i knew in my mind there was NO way they could possibly break them up and have starco and have that actually work.
Tom going through development as a character to be a better friend to star and rekindling their relationship from both growing is actually a pretty legit nice conclusion for those characters. It also would've been subversive to not have star and marco get together and tom and star's relationship could've easily been perfect to tie into the monster and mewman conflict.
In a way, it feels like tomstar would've been a perfect endgame for the show that tied into it's themes.
To break them up for starco not only feels extremely cruel to tom BECAUSE they addressed his self loathing issues, loneliness, and how he felt second in comparison to marco....but also it completely wasted a relationship that could've given growth to both characters and added to the series. It baffles me that the crew chose star semi abusing tom over a rather unhealthy obsession with marco as "The good ending" over star moving on in a healthy way from her crush and learning to be a better partner.
And yeah, jackie got screwed for no reason because a one episode conflict, kellco got a breakup offscreen for no reason when the reason they started dating was to get over their previous loves to make themselves feel better, Why even say that if marco just never moves on and gets star anyway?
It feels like the crew cared more about starco being canon, then how they actually developed them as a couple. Even now when booth buddies is addressed they care more about the fact starco kissed in the episode, then the cheating implications to tom or the fact in context a creepy older man forced them to kiss.
If they had ended on tomstar/kellco/jarco as endgame, and just didn't bother with forcing starco, they would've been better for it to me. All of those ships were far better to make endgame.
And to me, if the crew really could'nt handle making starco date in the show earlier because they thought it wouldn't be "Exciting", when they could with all three of those others, then maybe starco isn't the ship you want for your endgame, just saying.
But even aside from all that, yeah, s4 is by far the weakest, lots of wasted elements, weak villians and nonsensical choices made.
The fans have made far superior works using this show and the wasted elements and at this point might as well check those out instead.