What is ex acts like i meant nothing?

Assuming you are referring to someone who has treated you as if you meant nothing to them, exhibiting a behavior commonly referred to as "ghosting", here are some possible explanations for that behavior:

1. They may be emotionally immature and unable to handle the discomfort of ending a relationship or conversation in a mature way. To avoid confrontation or being seen as the "bad guy", they choose to cut all ties without warning or explanation.

2. They may not have been as invested in the relationship or conversation as you were, and therefore didn't see the need to provide closure or make an effort to maintain contact.

3. They may be going through their own personal issues, such as depression or anxiety, that make it difficult for them to communicate effectively with others.

Regardless of the reason, it's important to remember that their behavior is a reflection of them, not you. It's okay to be hurt by their actions, but it's important to prioritize your own well-being and surround yourself with people who uplift and support you.