I have no doubt your intention was pure, Amara 
You simply wanted to protect your boyfriend and his creative ideas- it’s a very noble intention and there’s nothing wrong with that!
Sometimes spells, especially spellwork that falls in what some would consider to be a “grey” area of magick (things such as binding, banishing, return-to-sender, cord-cutting spells, etc- not Baneful Magick but, as they involve casting magick on other people, are also not entirely Wholesome Magick either) can go in directions other than we expect them to. Anytime a spell is turned on or directed towards someone else, there is some risk of it having negative or bad consequences on the other person.
For example, casting a “Return to Sender” spell protects yourself or someone dear- but the results of that spellwork mean that the original spell caster takes the hit instead. As someone who believes in karmic justice, I personally don’t have a problem with “Grey” Magick like this- I see it as a protection spell that invokes the hand of justice.
However, there are some witches who believe that casting any spells that have an effect on others is wrong and cast only on themselves. Other witches have no problem with it, and some are even content to cast Baneful Magick (sometimes called “Black” or “Dark” Magick- think curses, hexes, etc).
Everyone is allowed to choose for themselves- if you haven’t already, I recommend taking some time to build your own personal magickal code of ethics to lay the lines of what you feel is okay and what you believe is wrong. It’s a great way to connect with yourself and your Craft! 
I hope that made sense- congrats again on your spell, and I wish you all the best!