From my experience, a guy shouldn't think he has to find a girlfriend before his hairloss gets bad. Some women, who you think you know well, are so shallow that they will dump a guy that they have been with just because their guy's hairloss becomes more severe.
You would never suspect certain girls to do that, but when it comes down to it, they will do such things. They feel justified because their balding boyfriend "changes." He, at first had decent hair without very noticeable baldness, suddenly becomes noticeably bald.
All the sudden the shallow girl isn't as "attracted" anymore to the same guy. The shallow girl also is ashamed to bring her "balding boyfriend" around her cirlce of friends - especially her girlfriends who she regularly competes with and compares herself to. The bald guy is no longer a "trophy" that can be shown to all of her friends for bragging rights, or whatever.
A true girfriend will want the same guy - bald or not. If a woman bases her male relationships on the guy's looks (a lot of women do this), then she isn't worth it. She's shallow. And a bald(ing) guy would be a fool for falling for such a shallow girl.