Can or should I ask my significant other to stop talking and to not associate with his ex? If so, how?

The answer to whether or not you should, would depend on the reason that you want your significant other to stop associating with their ex. Is your concern related to his well-being or is it a concern stemming out of your own insecurities? Understand that if it is a matter of jealousy, you need to consider that it might be a selfish choice to ask him to not associate with his ex. Don’t take it the wrong way, you are allowed to be selfish sometimes, allowed to demand and expect certain things from your partner in a romantic relationship. But recognising the cause will help you approach the situation with a broader, more unbiased perspective. To be frank, you should communicate with him either ways. You should not expect him to stop associating with his ex after the conversation if it’s a matter of jealousy. He may decide to stop associating to relieve you of your duress, but remember it does not fall in his obligation to do so. As for how you should communicate your distress, you can simply start by saying that something has been bothering you and it would make you feel better to open up to him about the matter. When communicating, remember to focus on your feelings. For example, instead of saying “I don’t think you’re spending enough time with me,” consider saying, “I feel a little neglected.” Find the emotions behind a particular behaviour, label them and take accountability for them.

Partners are meant to respect and honor your feelings and wishes. If there is something causing you emotional stress, I encourage you to express it in a calm, collected way. There is nothing wrong with being open to your partner about how they or their actions are making you feel. In order to come to a place where both people feel respected, it's very important that you don't invalidate their feelings, but actually fully listen to their thoughts and take it into consideration before responding. You know the situation best, so I hope my words helped give you understanding on an approach that encourages positive results.

This depends on how you feel about it. If you feel that you are uncomfortable that your partner associates with his ex, having a conversation with him and letting him know how you will might help you out. Openly talk about how you feel so that he gets a proper idea about his his association with the ex affects you. That might be helpful to you.

I would explain to your significant other how much it bothers you and why. It is then only up to them what they decide. If you don't like their choice move on

Start by saying "hey look it buggs me that you still talk to your ex" being honest is key, start the conversation, talk about it. The conversation may not end in the way you want it but it will help.

Yes. If it makes you uncomfortable that he is speaking to his ex, it's perfectly reasonable to ask him to stop. You should tell him how it makes you feel (jealous, angry etc).

If it makes you uncomfortable that your partner still associates with his ex, you can tell him about it. Just tell him that it makes you uncomfortable that he texts and associates with someone he used to be romantic with. It's perfectly ok to ask him not to especially if you don't like it. He can still associate with them if he pleases though, you'll just have to trust him if he continues to do so.

You are in all your right to speak your mind about what you're comfortable with and with what you're not. Communication is the key, however in order to really get to the core of this situation and make it viable for both of you it would be important to ask yourself what bothers you about it, what role you play in this situation, etc. So you can explain to him (calmly) what your boundaries are, how you feel and why. Giving some self reflection to this issue as well as try some proactive communication may be a good way to figure what needs to be fixed and how.

Romantic relationships are based on trust. Many people have strong friendships with their ex, who may have been with them through a turning point in their life. Talking to an ex is healthy, provided it does not jeopardize your SO's ability to support your relationship.

If you're feeling uncomfortable with your significant other talking to his ex, maybe instead of flat out asking him not to associate with them anymore, you could try just talking about how you feel and seeing if you can come up with a way you're both happy.