The New Kids On The Block star popped the question to 'The View' presenter earlier this month after her 11-year-old son, Evan, who she has with her ex-husband John Mallory Asher, gave him his seal of approval.
A source said: ''Donnie asked Evan if it would OK to ask his mom to marry him.''
After Evan said yes, Donnie enlisted him to deliver handwritten notes with the words ''will'', ''you'' and ''marry'' on them to Jenny before he appeared wearing a T-shirt printed with the final part of the message, ''me?''
And the insider told Us Weekly magazine: ''Jenny is incredibly happy with Donnie and vice versa. He's really supportive of everything she does.
''Donnie is her rock. He's everything Jenny needs but has never experienced in a relationship.''
The couple don't plan to get married until next year, however.
The source said: ''(It) won't be as big as her first,'' but it will be ''classy and chic.''