I believe they can be done, but I don't think they benefit anyone involved and I would view them as having the same dark implications that curses have. I don't know, maybe there are circumstances under which they could be justified - I just can't think of any myself. I don't like the idea of manipulating someones emotions, whether you use magick to do that or not.
I know how I would go about writing a love spell (I tend to write my own spells) like what tools/materials/ingrediants/symbolisms to use, but I never have, and it's not exactly something I plan to do.