couldn’t get an erection when’s losing virginity?

Yesterday me and my girlfriend were home alone. We hadn’t fooled around earlier in the day and had both gotten oral and come. This time we decided we wanted to have sex. But for some reason I couldn’t get hard. Eventually after trying with her mouth we decidedly to give up and do it when the time felt more right. I was embarrassed. Is it because i had come so recently? i feel like a loser and i feel like she thinks i am too.