>>55295455RPG Maker XP is what you use
Editing text is pretty easy, just find the event you want to mod and you can change/add text pretty easily
As for the romance thing, that'll depend on how much you want to do with it
If you just want to change dialogue to add it in, that's not too hard, but it's a good bit more annoying to actually make new events and making sure they trigger at the correct times, I assume
