This is probably Carole Nelson Douglas' Sword and Circlet series. "Six of Swords" (1982) is the first one, so matches the timeframe of over 30 years ago.
The plot elements, including the cat, are much as you describe.
Unfortunately, my answer can't be much more definitive than that. The internet is proving elusive at details, probably due to its relative obscurity. I may have a copy of Six of Swords at home. If so, I'll dig it out and expand my answer.
Edit: way back in 2003, on rec.arts.sf.written someone asked a story ID to which the answer was Six of Swords. The question fits the description of the heroine having magic via colorful eyes and the hero being a warrior.
I read a book back in the 80's. If I remember correctly, focused on a
woman and I believe her companion. The woman has silver eyes
(although i don't think it is "The Girl with Silver Eyes") and that
was the source of her 'power'. She was either able to work magic with
her eyes or had telekinetic powers. But as she used her power, the
silver in her eyes would diminish until she finally used all her
power. Her companion, I believe, was a warrior type. I've done several
searches on amazon and at my local bookstore but haven't come up with
anything yet. Any help?
In another rasfw thread in 1997, about cat based fiction, a poster called A^3 wrote:
Well, Carole Nelson Douglas seems to like talking cats. Her series of
Six of Swords, Exiles of the Rhynth, Keepers of Edanvant, Heir of
Rengarth, Seven of Swords
features a talking cat main character
matching another clue.