Even though it appears to be common knowledge that he didn't want a long term commitment, 3 years is (in my opinion) already one.

If she's been driving back and forth those three years between him and her cats, she's probably grown more attached to him and less attached to her cats, thus allowing her to justify doing the hard decision it sounds like she had made regarding them.'

I guess I wouldn't be surprised if she's overly sensitive about the topic since it's been something she's been dealing with for as long as she has -- and since the future is unknown, she's probably doubting herself.