The Kedushas Shoshanim says perek 17 seif 4 that yur not aloud to look at yur wife undressed even when tahor. This is from Avrohom Avinu who never looked at Soroh so that we didnt know how beautiful she was until he acidently looked at her reflection in the river. This isnot a chumra but actual halachah. So swimming with yur wife is 100% assur. Theres nothing to talk about.
I know this is off topic but I head very differently. Of course Avraham looked at Sarah but he saw her as a whole person, inside and out. Think of your good friends, if someone asked if they were good-looking based only on their looks, it’s hard because you see them as a person, not as just what they look like. So then when they were going to Mitzrayim, he saw her reflection in the water which was pure gashmiyus, he realized how pretty she was. (I think this was a Rashi)