I don’t think you’re really losing your attraction to these women; I think you are afraid of getting more deeply involved with them and it’s causing you to distance yourself. When you’re in fear mode, it’s really easy to look for minor flaws in people (which we all have) and turn them into dealbreakers so that you don’t have to take the chance of getting hurt. You can lose sight of your attraction and feelings for the one you’re dating when you’re focused on what she’s lacking.

I used to be kind of the same way. I used to break up with guys who I actually liked because I was afraid of taking a chance with them. There’s a therapist/blogger named Sheryl Paul who writes a lot about "losing attraction" to people we actually feel a strong connection with, and her stuff really helped me a lot. I’d suggest reading her: https://conscious-transitions.com/for-men-when-youre-not-attracted-to-your-partner/