Clearly some folks here like simple answers to complex problems.
It’s a positive thing thay she recognises that she is being irrational at times, does she?
I think framing it as ‘her’ problem is not useful. It may be a trait of her’s but the problem is something you both experience. To see it as separate to you is a hint that you might being seeing yourselves as 2 people living together rather than a single unit. This may be cause or effect, either way it is not sustainable. However, walking away is not the answer, yet. Deal with this together, get help together. Start soft with an appointment at Relate or similar,
If you both want to get better.