Boyfriend became a sponsor!!

Long story short my boyfriend became a sponsor to help his friend get a green card. He’s known his friend for 2 years. Me and him have been together for 5 years, and he never even told me about it. I’m not angry for him doing it because I understand.I’m just upset that he didn’t even tell me. I only found out because when his friend called he brought it up. Should I even be upset for him not telling me?