Both are correct.
"This gentleman asks his girlfriend, "Will you marry me?"
Please note added comma, capital and question mark.
"This gentleman is asking his girlfriend, "Will you marry me?"
Please note added comma, capital and question mark. I prefer this example, but the first is fine.
If it is a caption for a publication, you can drop some words:
Gentleman Asks Girlfriend to Marry Him (More capitals, no commas or periods.)
If you are meant to describe the image:
The young man is proposing. He is down on one knee and has brought (brings) his girlfriend gifts to show how serious he is about his proposal. The young woman looks quite disinterested.