Many people tend to stumble in intimate relationships; actually, the key isn't "how well they can talk," but rather a few very obvious points.

The first type has very large emotional swings, initially treating you very well, replying instantly, and being very infatuated, but as soon as something is slightly displeasing, they immediately turn hostile, curse, or use cold violence, seeming like two different people before and after.
This type is basically emotionally unstable; it's best not to try to change them—just withdraw if you can.
The second type is more covert, appearing very polite and easy to talk to on the surface, but internally they are constantly keeping score, not expressing their unhappiness openly, bottling it up, and then suddenly exploding at a certain point, using cold treatment or passive-aggressive ways to torment you, making you unable to pinpoint what’s wrong but feeling very exhausted.
The third way to judge is simple: observe whether they use a "we" or "you" perspective during chats and arguments.
If they always say "I feel," "I am wronged," or "I am being treated this way," with no reflection or empathy, they are basically living only in their own feelings, and the relationship can easily become one-sided, draining you.
The fourth type puts their entire life focus on you, with no friends or hobbies—saying "I only have you" sounds very heartfelt, but actually puts a lot of pressure on you.
Once separated, they may find it very hard to accept, increasing the risk.
Overall, if someone exhibits emotional extremes, lacks self-reflection, is overly dependent, and has strong possessiveness, you should be alert.
This is often not just love but an unbalanced relationship that may even carry risks.