Someone once asked...
Someone answered with kindness...
If you do not tell them, it will turn out worse in the end - catastrophic even. It feels small now and you might think, just ignore it and it would go away or you can manage. But what would happen is that your resent would grow beyond what you can imagine. So you face the choice of short-term pain, vs long-term amplified pain. Take the risk to tell them. Do not tell them when you are annoyed, or when something just happened. Wait for a time when you are both in a good mood, things are going well, and your love feeling for them is high. Affirm them first, what they do well, how you appreciate them. Then point out the things that bother you. Check your motives carefully - what result do you want out of that conversation. Should they change a behaviour. Do you just want to be understood. Or are you trying to hurt them (I know you are afraid of doing that by the premise of the question, but it could be there subconciously). Make sure your goal is clear to you, and then communicate humbly. Even if they are defensive, it does not mean that they did not hear you. People still reflect on things even if they are defensive. So just say it, and explain it, but do not try to insist on the point. Pray first and go for it!