Most of the VNs have some sort of romance, but there are some that are about true love overcoming all difficulties. Of a pair of destined lovers overcoming every difficulty...

Examples include:
*Stories about lovers that stay true to each other no matter what (lying once or twice allowed sleeping with others not),
*Stories about lovers that sacrifice everything for their love,
*Stories where love saves the characters from certain doom (like giving up on an endless chain of revenge for love),
etc