Fucking things up in your life or his, meaning that there may be some unexpected or unwanted outcomes. Demons tend to take the path of least resistance so this is a possibility.
A hypothetical example would be that you do the spell, it works, but later on it all falls apart and you’re left with a broken heart and a self esteem that may be hurt. Another example would be him becoming “creepily” obsessed with you and then have to do jump the magical hoops just to stop it.
Just make the petition from your heart and exactly what you want. The formula is not as important as manifesting your will. I know it may seem obvious or unhelpful but trust me there’s plenty of love spells and/or petitions on the forum and YouTube. Just put in the search “love spell petition”.