How did my mate romance a girl who'd already turned him down?

Every girl is different. I don't, however, think many of them would much appreciate being texted a picture of any part of your anatomy. Well, some may think it was funny - but doubt it would make many want to date you. Try asking your mate what he did. And what worked for him may not work for you. Some women could be converted by being pursued - not as in stalked though. Just continue to try to be friends - and unless they are adament about not wanting to go out with you - being very very nice and continue to ask them out. Maybe bring them flowers or something sometimes. Just continue to show your interest and be nice - and who knows?