Provided the gods of Rome are given their due, it doesn't really matter to them whether their worshippers believe in them or not. Having taken part in the official rituals, a citizen is free to worship whatever other deities he pleases. Rom'es gods are there to be obeyed and respected, not loved, and they no more mind sacrifices to other deities than the taxman minds people paying other dues elsewhere. Dealing with the gods is an exchange of duties and mutual respect. Confessing a deep love for a particular god is superstitio and the person concerned is probably emotionally concerned.