“向某人求婚”常见的英文表达是 “propose to someone”。
例如：
He planned to propose to his girlfriend on their anniversary.（他打算在他们的纪念日向女友求婚。）
After dating for three years, he finally proposed to her.（交往三年后，他终于向她求婚了。）
此外，也可以用 “ask someone to marry one” 来表达类似意思，不过 “propose to someone” 更为常用和地道。