Yael, have you tried using the bath for "water play"? As in put water in it, and maybe bubbles or coloring and getting some toys and then just playing in it with him - not getting in, just kneeling/standing next to it like it's a trough and you both getting drenched and having fun. I know this might be difficult pg, maybe your DH could do it with him instead? Just a thought - once he thinks of the bath as fun again it will hopefully solve your problem. GL with it.