Definitely, everyone will offend you at some point, and there is nothing you can do to prevent this from happening. Some may apologize while others may not be aware of offending you. The only thing with your power is how you deal with the offense when they came.
There will come a time when you realize that your peace of mind is more important than what your partner did to you. Forgiving someone's sins doesn't show that what they did was right, and you at fault, but the act of forgiveness will benefit you more.
Unforgiveness will do more harm to you and your peace than the person who offended you. Just because you forgive them does not make them your friend, nor does it make them your enemy. You don't have to keep bearing malice with the person, because sometimes, they might have offended you unknowingly. For instance, they may find themselves caught between two terrible choices and at last, they chose the one with the least consequences, and unfortunately they offended you in the process.
You don't have to wait for the person who offended you to say sorry. This is why there is such a thing as Pre-forgiveness. Pre-forgiveness means forgiving someone in your mind even before they offend you. Therefore, when they offend you, you won't be surprised.
You will agree with me that there is a kind of feeling that often arises when you suddenly meet someone with whom you have a grudge or unforgiveness; Your heart will skip a beat, your stomach rumble and all. Proves that you are hurting yourself more by being unforgiving.
Forgiving people may not be easy, especially when their crimes seem unforgivable, but when you think about your own peace and happiness, you have to make a choice to forgive them for your sake. When you weigh the negative consequences of unforgiveness against the benefits of forgiving, you will chose forgiveness.
There are times when you need to consider the intentions behind the actions people have taken to offend you, as it may help you forgive them easily. Being unforgiving, for the most part, are functions of the mind. This is why you should not let what your mind perceives about someone to dwell so much on the negative. Let forgiveness rule your heart always.