Irene was both attracted to Clare but also extremely jealous of her. I think a part of Irene wanted to "pass" as white as well. The beginning scene hinted at this when she was passing at the hotel. You could see the mixture of guilt and exhilaration she had when she realized people thought she was white. But she couldn't fully commit to it. And even though she didn't deny her blackness, was married to a black dude and was raising two black boys she still had a few
tendencies. Like her refusal to talk about the "racial problem" with her kids and how mad she got whenever her husband told their kids about what was really happening to Black folks. Also, the fact that she had a black maid and how close she was to her white associate.
Irene was also jealous of Clare's ability to both pass as white and enjoy that privilege while still being able to mingle with black folks. Finally, she was jealous of her relationship with her husband and how it seemed like her husband was more attracted to Clare. You mix that in with the fact that she was lowkey attracted to Clare as well and you could see why she was so conflicted. And I like how they left the ending ambiguous, how you weren't sure if Irene was trying to protect Clare from her white husband or if Irene was the one who pushed her out of the window on purpose or if it was a mixture of both, added to her conflicting feelings.