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

If it's making you uncomfortable with it then yes, of course. Never put yourself in a position where you may not be happy just so someone else can be. If he has a problem with how you feel then ask yourself how much he really respects you.

That isn't for you to decide because it's his choice and freedom if he wants to talk with his ex or not. All you can do is be supporting and understanding and to be patient.

Yes ! You should definitely talk to them about it , the person is an EX for a reason meaning its EXpired and if your partner is not willing to stop associating with the ex they probably still have a little feelings for the them.

I think it depends on your motive for asking. Are you asking out of insecurity or are you asking because your significant other is behaving inappropriately with his ex? I don't believe there is black-and-white answer for this - some exes can remain good friends after they break up, some cannot, and some continue being more than just friends. You really have to look at the behaviour and intentions of everyone involved.

You should have a talk with them let them know but ONLY if it bothers you not because you're jealous or have trust issues.

So I'm in this situation. I'm not comfortable at all but my partner tells me he wants to gently remove her from his life because she has a mental health issue and does not want push her further. I agreed with this until I found out one of 2 things recently. 1. She wants him back after a year. She constantly checks to see if he and I are happy. Constantly messages to ask if he's ok because 'she felt a vibe' and is using social media to get his attention. And 2. We were looking at a business and he informed me he would have to check with her to see what she thought. If she thought yes then we could if she thought no then we would not. That's my boundary. Absolutely not will I tolerate that. I knew a while ago that this contact was not going to end well but stayed because I believed his initial reasoning. Absolutely not does anyone have the right to tell someone they can't be friends with another person. But if your reasons for that are valid and not just out of jealousy then you have the absolute right to decide not to be ok with that and leave. If you're honest with your reasons and your partner can see it hurts you then he/she should take that in to consideration. You should always be the priority to your partner, not the ex and if you're not then it's on you to decide whether you stay or go.

If you are in a serious relationship (engagement, marriage) then yes you can ask for that. Such a serious relationship should be built on love and trust, either of you should be willing to do anything and give up anything, for the other. You on the other hand also have a responsibility to understand the actions of the other and assess whether it really is bad or no.

If your partner has no children or shared business with their ex, you should ask that they close the door of the past and stay here in the present. Sometimes your significant other has unresolved feelings about their prior relationshiops. In this case, your partner should be actively involved in working through their issues with a therapist, mentor, or trusted spiritual-advisor. If not, unresolved emotional baggage may be affecting their present life in undesirable ways.

Yes, you CAN ask them not to associate with their ex, but there is a difference between asking and demanding. Let your significant other know that it bothers you and why. It really depends on how you go about it. If you lean towards forcing them not to talk with their ex, then it shows that you do not trust your partner and may only lead to further disputes between the two of you. It should be up to them if they stop talking, and if it TRULY bothers you, then hopefully they will respect your wishes, but at the same time it's unreasonable to expect people to completely cut off ties with people because we want them to. If the relationship with the ex seems a little too "close", then maybe just share your concerns. If not, then your partner may just take it as you not trusting them.

When in a relationship it's a good idea, early on, to establish "boundaries": what's expected from each other, what are the no-no(s), what's preferred, and what should be limited to the minimum. Dating is about getting to know someone, getting to know ourselves, and see if this someone and this relationship is something we want for longer time; therefore a good relationship is between 2 compatible and like-minded people. If there are behaviors/needs that one has and are not compatible with the other.. it's a sign of incompatibility. Small issues can be negotiated or overlooked, larger issues... are a clear sign that the relationship is not meant to be (for the long term). Best to get things out in the open, clear and unequivocally early on, than leave things unsaid that, sooner or later, will come up with disastrous effects.