How do couples navigate financial mistakes?

My fiance and I are having trouble navigating financial mistakes. Like this year we've had over 2k in scams, "free" trials, and make money fast opportunities that didn't pan out. My fiance made all these decisions and he brings it back on me like "well we made these decisions together because I convinced you to let me do them" and I wanted to put faith in and trust in him but now I know he just isn't very financial savvy and that's okay. I know couples make decisions "together" but also like how would you navigate this? I'm so tired of working 2 jobs to make up for his short comings and I'm soooo drained. I don't want to say anything that accidentally comes from a place of exhaustion.
How do couples navigate financial mistakes?
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