When talking about a strong passion or obsession with something, the phrase "was nuts about" can easily be substituted with other synonyms. One alternative is "was crazy about", which conveys a similar level of enthusiasm. Another option is "was obsessed with", which implies a more intense and potentially unhealthy level of attachment. Additionally, one could use "was wild about", which suggests not only a strong attraction but also a sense of wild abandon and excitement. Overall, there are many ways to express a deep fondness for something or someone, and each synonym carries its own unique connotations.