Keep in mind that these are speculative and may not apply to your situation directly.
Fear of Commitment: Your ex might be expressing a fear of commitment or responsibility associated with having children. They may not be ready to take on the responsibilities of parenthood, especially if the relationship has ended, and they don't want to be bound by any obligations.
Communication of Boundaries: Your ex might be setting clear boundaries regarding their involvement in your life. By stating that he won't raise the children, he could be signaling that he wants to move on from the relationship and does not wish to be involved in your potential future family life.
Emotional Distance: It's possible that your ex wants to distance themselves emotionally from you and any potential future consequences of your relationship. Making such statements could be a way of detaching themselves from the situation.
Unresolved Issues: There may be underlying issues from your relationship that have not been addressed. Your ex's statement might be a reflection of unresolved conflicts or emotional baggage.
Reproductive Concerns: Your ex might be worried about the implications of an unplanned pregnancy or the possibility of becoming a parent before they are ready, financially or emotionally.
Communication Style: Some people may choose to be upfront and assertive when discussing sensitive topics, and this could be your ex's way of expressing their feelings without sugarcoating the message.
Remember that communication can be complex, and there may be nuances to your ex's statement that are specific to your relationship dynamic. If you're uncertain about their intentions or feelings, it's essential to have an open and honest conversation to gain clarity and avoid misunderstandings. However, it's also crucial to respect their boundaries and decisions regarding parenthood.