Sometimes if the female is too fat and the male is inexperienced, they will often fail embracing and eventually one or both will become frustrated and give up/exhausted.
If female is too fat, her egg passage is often blocked making it hard for her to release her eggs. These females need bigger/longer males. Persistent pairs may take a full day embracing and still not done. In which case the female usually releases her eggs after dark. But if the female is only fat from eggs, usually she will release some unfertilized eggs so they can embrace better. In any case, you will probably have a small spawn.
Fat males too have difficulty embracing properly. An ideal male is a slim and slightly longer male. But this doesn't mean smaller males can't breed with bigger females - as long as both aren't too fat, they will get it done.
If the female has given up, I suggest taking her out. The male may attack her. But if she is still responding you can give them more time.