A "60 Minutes/Vanity Fair" poll published in 2013 reported that 45 percent of people believe that a man should ask his future father-in-law for his daughter's hand in marriage as a sign of "courtesy." However, 3 percent considered the ritual "sexist and offensive." Because people have mixed feelings about this tradition, before you get up the guts to talk to your girlfriend's father, you must first consider whether you should ask him at all.
Consider why you might ask. If your girlfriend or her father is a traditionalist or holds certain religious beliefs, it will be considered a sign of courtesy and respect to ask for permission to marry. Engaging in this kind of ritual can be a bonding experience and a good start to your future role as a son-in-law. Some women feel that in this modern era of equality "asking permission" is a moot point, especially since marriage is no longer a financial transaction between two families. If you're unsure about whether to ask, talk to your girlfriend. You should also be pretty confident your girlfriend will say yes to your proposal before you ask her parent.
Consider who you might ask. If your girlfriend doesn't have a good relationship with her father, if she and her father are estranged or if her father has passed away, it might be a nice sign of respect to ask another caregiver for your girlfriend's hand in marriage. For example, you might ask her mother or a grandparent. This might be a nice way of showing how important that caregiver has been in your girlfriend's life.
Meet with the father (or other caregiver). If possible, meet with the father in person. Ask him to coffee or ask for a private talk the next time you visit. Tell him how much you care about his daughter and then share some qualities about her that you love. All parents enjoy hearing glowing reports about their children, so this is a good way to bond over someone you both love. Tell him that you want to continue to care for her for the rest of your life. And then ask. You may not want to specifically ask for "permission" if his answer wouldn't change your intentions. So ask for his blessing.