My ex and I broke up 3 months ago, we have issues to resolve such as my things and car insurance and he won't respond to my txts. Why?

Relationships are extremely complicated and there are many emotions tied into each one. It is important in relationships to not place too much of the blame on yourself. Many times people have very different ways of dealing with emotions and your is most probably just taking their own path to responding to this situation. It would be really hard to place a perticular reason as to why he is doing this but as I stated before the most important thing is to keep in mind that you cannot place the blame on yourself. Keep moving forward and everything will eventually be resolved.