Fatal error: Allowed memory size of 1610612736 bytes exhausted (tried to allocate 4096 bytes) in phar:///usr/local/bin/composer.phar/src/Composer/DependencyResolver/RuleWatchGraph.php on line 52
Check the memory_limit:
php -r "echo ini_get('memory_limit').PHP_EOL;"
Locate php.ini
php --ini
Edit php.ini
nano /Applications/MAMP/bin/php/phpx.x.x/conf/php.ini
memory_limit = -1
Try again