Look up the DAFT visa in the Netherlands. (Dutch-American friendship treaty)

My advice would be NOT to pursue a partner visa only because you’ll have to prove to IND you can financially support him. That’s a lot of responsibility on your part. If he’s graduating from one of the top 200 universities, he can apply for an orientation visa, come and live with you while he looks for a job. I’d advise him to save some money up before he does since he won’t have a job when he initially comes. The process takes about 6 months.

https://ind.nl/en/residence-permits/work/residence-permit-for-orientation-year#Designated foreign educational institution