The whole story just turned around to be not what was originally described.
Brian said that she’s fully dependent, so he’s been saving money so she didn’t have to work when she moved with him. In addition he planned for her to cook and clean in his house when she moved in with him.
Well it sounds that she’d have to give up a lot to be with him.
Give up what sounds like a good job, become dependent on Brian, cook and clean, which we don’t know if she does that at home or not. If her and her husband are well off, she likely has someone to clean the house. Now she’ll have to do cleaning. All while depending on Brian.
It doesn’t sound that she has fear of change but rather is hesitant to give her entire life up. She’s not acting impulsively and that’s a plus. Perhaps her affair seemed exciting for her at first or perhaps she got into it while manic or intoxicated (if she really is bipolar and has substance abuse problem). She might also feel remorse leaving her husband as he’s getting old. He doesn’t sound like bad man who deserves to be dumped in old age with no warning.
Now she’s told to give up so much, her opinion on the whole thing changed. 50 year old woman is smart enough not to give up her job and independence and go cook and clean and depend on someone she barely knows. Having bipolar disorder is irrelevant here. She was originally described as someone unable to make decisions, but it’s actually quite the opposite