relationship indecision

What do you suggest when someone is struggling with deciding on a partner – Is the person I’m with right for me?
How much should I “compromise” or recognize that no one is perfect?
I wondered a good amount about this earlier in my life – however I leaned away from marriage with all the guys I dated, until I met my soon-to-be-ex-husband. Ironically I thought he was wonderful and was delighted to marry him. It turns out I wish I didn’t marry him, but I didn’t know that at the time.
Now I’m wondering how I will decide upon my next partner, as I’ve started dating now – I’m thinking we might say to just listen to what feels good to me, but that didn’t work the first time around so I want to trust myself but feel that when I did that it worked out poorly for me.
I also know some people in relationships that are in a lot of confusion about if their partner is right for them… I’m imagining I could be in that spot once I start dating someone seriously. There is the fear of choosing incorrectly and the fear of losing the right person.
Thank you for your help.