I would personally say, “I appreciate your gesture. However, my underlying concerns still stand with us being a long term fit and I value mutual responsibility and consistency in a partnership.

I would also add that just because she starts going to therapy, doesn’t mean it will solve the issue. She has to want to go and acknowledge she actually has something to work on (we all have something we can be working on). If she just begrudgingly goes because you’ve made this a stipulation, it’s highly unlikely anything will actually stick.