Maybe he's a more desirable candidate for the job he applied for. It could be your resume. It also depends on what jobs you've been applying for versus what he applied for. I'd also suggest maybe calling or actually visiting the location where you applied to so they know how interested you are. I did that for the last job I had. I do understand your frustration though.

What are your respective degrees/skills, and what kind of jobs are you both applying for?

Maybe he is just better than you are. Ask him for help.

Ten job applications in three weeks isn’t even one a day, maybe you should be more diligent if you really want a job.

It’s about being at the right place at the right time

Maybe take a look at his resume and cover letter to see if there is a huge difference in style. It does make a difference with companies that scan before having someone look at what passed the scan. You may need to spruce up the writing to sound excited about even boring responsibilities. I reworded my nephews and he started getting call backs. Didn’t lie. Just write it up differently. You are selling yourself. And your soul.

If I’ve learned anything from this site, it’s to make sure “I love ******** “ isn’t discretely put on your resume by someone else. You better check.

Come back to complain when it's months and not weeks that you are talking about.