Is there any marriage that never had hard times?

I (30F) am asking because I have had a super hard time in my marriage (been togther for 6yrs, and married for 2yrs) since 1 year ago, due to in-law relationship.

There were a lot of tears, and frequently very hard, long and challenging communications. Some of them turned into arguments (not just about in-law anymore) in the end.

It has been better since a few months ago, but still somtimes I think about whether I should stay in this marriage or not.

Now what made me want to stay are:

1. Nothing is significantly wrong with me and my husband.
2. For the most of the time we are lovely and living a very happy life. We have pets which we both love so much.
3. My husband is a very good man, he is loyal, funny, self-discipline and supportive for most things. He is very loyal and also learning to be more caring and considerate. He has a great job. I am earning much higher than average for my age, and he is making 2x or 3x than me.
4. There is nothing other than the in-law problem that is bothering us. And it seems like my husband is now ok with me not seeing them (even though I'm not sure if he would change his mind).

But still, even though our time is 95% super happy, that 5% really hurts.

So, is there anyone having an amazing relationship that has never had any very challenging time? For those who have been staying together for a long time, was there any hard time and period? And do you regret not leaving?