If your partner punches you once and apologizes immediately, should you still be wary of him/her hitting you again?
Have you ever accidentally punched someone? Me neither. Once they find that they can get away with it, it will happen again and again, until it’s a regular thing. Do not accept their apology.
It’s extremely rare that it only happens once. Honestly, once should tell you all you need to know about the person. Violence doesn’t equal love. It’s a weak attempt at dominating and controlling because they lack the ability to reason with you and talk things through. Leave while you can.
If you’ve decided to accept his apology, but still have some remaining doubt that it won’t happen again. Will the wariness have a negative effect on your relationship in the future?
You shouldn’t be questioning whether wariness has a negative effect on your relationship, it’s the abuse that has a negative effect. Imagine the next time you argue. Will you trust him/her to restrict himself/herself to verbal aggression only? Will it be in the back of your mind every time he/she raises his/her voice? Will you fear what it could lead to? If you answered yes to any of these questions, you need to get out of this relationship as soon as humanly possible.
Don’t shoulder the responsibility of making excuses for him/her or telling yourself he/she didn’t mean it. He/she meant it.