Falling in love while helping a cat woman return to her Earth alone leaves an insular college student struggling to maintain his belief in her and find a way through the gateway.

Rivercoon,

All the previous comments to the older versions of the logline apply to the latest as well.

You need higher stakes and cinematic actions/events.

A romantic idealist returns a lost humanoid feline to her parallel Earth but must battle amorous advances and hardened skeptics at college while piecing together tenuous clues to reopen the gateway to the woman he now loves.

I didn't read the other comments, sorry if I repeat some of the others.

This is confusing at best. The MC is the student, but it is unclear what he wants and why?
What is the plot in this story? What event starts it, what motivates the MC and what is his goal? To get through the gateway sounds like a step on the way to achieving something else.

If the Catwoman is in danger and he just so happens to be the only one who knows it then you could make it out that his goal is to save her, but as it stands the motivation feels labored and the goal/action are unclear.

A nerdy college student's decision to help a lost hitchhiker from a parallel Earth get home leads to love. But when the gateway between worlds proves unreliable he must maintain faith in his memory of her while finding his own way through.

---A nerdy college student encountering a lost hitchhiker from a parallel Earth leads him to love found, love lost and a struggle to find his love again. So what if she isn't human.---
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In the latest attempt, your lead character isn't pro-active but is led by the cat woman. If this were the case that would make the cat woman the lead character.

However, if we stick with the college student as the lead, then I would recommend adding to the logline specifically what he must do.

Must the lead get the cat woman to a specific place where the walls between dimensions are thin?
Must the lead break into his own college science lab and get a scientific do-hickey so she can build a portal?
Must the lead seek out a reclusive astral physicist who can help them create the portal?

Specifically what must the lead do to achieve the goal of helping the cat woman back to her dimension? (And what is standing in the way)

Cat woman in outer space? Sign me up!

College student is the protagonist? ?I recommend focusing the log on him and his conflict and struggles, which is, I assume, the gateway?