Your partner's faithfulness fully depends on how you carry yourself in the relationship. What you do and how you treat him/her affects how he/she will treat you.
Here are some of the things that you should do if you don't want your partner to cheat on you.
1. Stop cheating
This is obviously the number one point; stop cheating. You don't expect your partner not to cheat if you are unfaithful. Be faithful and your partner will also be faithful.
2. Stop threatening to break the relationship
If you keep threatening your partner that you will break up with them then be sure they will be tempted to cheat.
Why? Because you've made yourself unreliable to them. They can't trust their future with you.
3. Make them feel wanted
How would it be when someone makes you feel wanted? You will feel happy and contented with the relationship.
But what if he/she never makes you feel wanted? You will have the urge to seek this feeling elsewhere.
So if you want your partner to stick to you, make them feel wanted.
4. Give them time
Time is so precious in a relationship. Giving your partner enough time and attention is what will keep them with you.
The exact opposite of this will lead to cheating and dishonesty.
5. Satisfy them in bed
This is an equally important point. In fact, sex really determines whether your partner will cheat or not.
Sexual dissatisfaction is the major cause of unfaithfulness in most relationships. So make sure your partner is satisfied in bed.