You hit the nail on the head Lizzybeth, if this is the case in this situation and the Mother's reasoning was that the boyfriend didn't want children.
Yes get another boyfriend! I did. Without qualms either, when I was a single Mother.
O/T but I wanted to add also, my only Brother is now 42, never married and he has no children (he's never wanted children). When he was younger he would not date women that had kids (he still doesn't). He was raked over the coals by many women that had nothing but ugliness to say about him because he wouldn't date them and they had children. He was made to be a monster in some of our social circles. Here was his reasoning---He didn't want his own children, he didn't want to have children at all, he refused to date a woman because of that and also, he said he refused to do that to the children, get to know them, bond and then leave. He said it would be cruel. But yet, he was actively pursued by many women with children. Strange.