There is a lot of difference in running away with someone you love and converting to his/her religion and copnverting only for the love of Allah (swt).
Infact Islam discourages conversions based on girl friend/boy friend love and marriage.
The religion of Islam is only for the sake/love of Allah (swt) and nothing else!
I can give you countless instances of the type you have mentioned, the only difference being the boy or girl reverted to Islam! But this is not conversion for the sake of religion of god but for the sake of your loved ones and their family and this is not encouraged in Islam.
