I am genuinely struggling to understand how he ended up in said hot tub without an element of prior planning (you need swimwear….) and how that didn’t involve some kind of natural conversation with you prior to going.
You know such as leaving the house with a bag, and you querying what the bag is for, or asking if you know where his swimming shorts have gone (and you asking why he needs them…) etc.
I just can’t quite envisage my husband going to someone’s house for a party, taking swimwear with him and that never having been mentioned in passing conversation in the build up to him leaving. Could it subconsciously be more along those lines that you actually feel uneasy? I couldn’t care less if my husband went to someone’s house and used their hot tub, but if that happened with me having no knowledge of the hot tub party in advance I think I would feel a bit strange about it, purely because I can’t quite see how he would have got to that point without me knowing, and so that would make me wonder if he had deliberately made sure I didn’t, or whether he was hiding something.
Honestly that’s the only possible explanation I can think of for you to feel uneasy as it’s just a hot tub. They’re not immoral, wicked or sinful. But that being said, I also just can’t envisage a situation where my husband ended up the only male getting in one at a party, he would rather stand around with his friends chatting. However, pre owning my own, I would definitely have hopped in with no other females just because I loved a hot tub so much, and there would have been nothing more to it. Maybe he just loves a hot tub….?!
All the blurb about being Christians etc is just nonsense (in the hot tub context, I am not saying the religion is nonsense but the correlation with incompatibility with Christianity if you get in a hot tub is just ridiculous). They’re not one of the deadly sins. However, another viewpoint worth considering is whether your (seemingly very strict) moral boundaries on what is and is not acceptable are actually your (singular) boundaries rather than your (plural) boundaries and perhaps your husband does nod along, pretends to share those views and then leans more towards letting his hair down when you’re not there - and you normally don’t hear about it. By letting his hair down I do not mean cheating, but your views seem very extreme - if a hot tub is seemingly immoral, what else is? There seems to be quite a strong discrepancy between your views here - you are shocked and appalled that he got in the hot tub, with a lot of background noise about your religion and morals and he clearly does not share those views because he….got in said hot tub.