Should I date a man who has two wives?

I met this girl online and we’ve been friends for a year now... i actually met her on a christian website.. she’s married... and she has a sister wife.... we know each other really well....she came to visit in the holidays...and we had so much fun just hanging out.. we talk on the phone most days.. she’s 23, her sister wife is 21, their husband is 47 and i’m turning 20 soon... i know that her husband is interested in me..as in marrying me... he told me that himself... we’ve never met in person..from my photo he said i was “stunningly beautiful”... im meething them all next month... her husband wants to go on a date with me...alone..so it will be just us two.. im really nervous about that... ok so i know there re a lot of things “wrong” with this picture... like the age difference..the fact that i met these people online.. and the polygamy part... but it feels right to me... i havent said yes to the date yet.. im still thinking about it.. it will just be a casual first date kind of thing..like getting to know each other... i could imagine myself married to him and living iwth them.. i love the girls..i know i’ll get along well with them... they have a gorgeous 14 bedroom house and i wont have to work because he makes enough money to take care of all of us.. this is what ive always wanted...i’m kinda old fashioned.. i want to get married and have babies....so i‘ll be sharing my husband..i dont see anything wrong with.polygamy... its not what you think at all.. not what you see on tv..where the woman has to cook and clean..and be submissive.. etc... my friend has a college degree... and she’s independent.. like i said..she drove down to see me by herself.. theyre christian but theyre not mormon or religious freaks...theyre totally normal people....so am i crazy for even considering this... im not making any big decisions now..but should i go on the date? and just see what happens?