Contact says a male name but has Snapchat as a girl

Okay so opinions... my SO has a contact under a male name (his friend I’ve never met or anything) which is also his sons name, one day I was calling someone for him on his phone because he was driving, I seen the contact, who has the same name as his son so I joked and said “*sons name* has a cellphone already” (he’s too young) clicked it, the number was there but also the snap chat name which was a girl?? Weird so I said u sure this isn’t someone else and he swears up and down it wasn’t, he said he’d call the number if I wanted but obviously I wasn’t going to go that far.. I mean come on. I then caught him snap chatting a bunch of girls, then it dawned on me.. I called this contact and it happens to be the girl the snap chat name is under.. now that I think of it I am pretty sure I’ve seen him messaging this contact a long time ago but I don’t watch over him when he’s on his phone it was just a glance but other than that I don’t know....

coincidence or what? I don’t know what to make of it,... is there something going on maybe I don’t know of or am I overthinking....