I'm dating someone who has cheated in the past. What should I do?

The fact that they may have cheated in the past doesn't necessarily mean that they will do the same with you. If you find yourself thinking about this often, do not hesitate to talk honestly, and share your fears.

You might try to find out, in an open conversation, which were the causes that made your partner cheat, so that you will avoid those issues in your own relationship. Then, both of you must always be open to each other, and discuss everything that doesn't feel quite well. Build trust, learn to forgive, and once everything is set and discussed, leave the past to be the past and live your own life together.

If you're dating someone, you obviously have enough trust in them. Just keep in mind that while there is a possibility that they may cheat again, but not a guarantee. Not everyone who has ever cheated is a "serial" cheater, and, as I said, if you are dating them you must have some faith/trust in this person that they will be loyal and faithful. Instead of focusing on the past, focus on the present, and how you feel about this person. The past is in the past, and everyone grows, especially with more relationship experience. Have a nice day! :)

Give him/her a chance, trust is crucial in a relationship, but be cautious as well, as he/she might repeat history

Try not to always trust them completely, but try not to make it so obvious. You should maybe ask them why they felt like cheating and if they would do it again.

Pay attention. Sometimes people do set themselves up to eventually become cheaters by isolating themselves (withdrawing physically/emotionally) or not fully investing in a relationship. The grass is always greener to the unhappy. Make sure you're actually in a happy relationship.

if they told you about it then that's really a good step and we should give them another chance like we all could do mistakes and it's not that past which decides the people it's the present and what they plan for the future

The first thing you should do to ease your mind is ask yourself if you are In a trustful relationship, in other words, do you trust her not to cheat? Once that question is answered it is always best to talk to that person about your fears and how you feel, because having a relationship without verbal communication can lead to misunderstanding and the constant feeling of doubt/fear. One thing I suguest Is to not make a rational decision on the spot you know you will regret or have no confirmation to. Just no matter what remember that everyone makes mistakes in the past and the person could have changed, never judge a person by their past!

If they have cheated in the past there most likely to do it again if you allowed it before they know they will get you back, I believe everyone deserves a second chance and prove they won't do it again all I'd say is to be carefully that you don't get your feelings hurt as a breakup is a very painful process.

Make a decision about them now. Find out why they did it and decide for yourself if you are willing to accept it. If you can't accept their past then there is no point taking the relationship further.