What I would do in this case is use a conditional tag so that the contact form 7 styles load only on the page that has a contact form.
I believe that the contact form 7 uses wp_enqueue_style() function to load its styles onto the page, so you can use the wp_deregister_style() function to remove it from all other pages. Here’s a link to a well written tutorial that explains how to do this in more detail:
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Support forum for Event Espresso 3 and Event Espresso 4.