I found my sister's boyfriend on tinder. Should I tell her?

skin_and_bones13
So i just started tinder and went on the swiping tour. Saw my sisters bfs profile. Made a screenshot, but didn't swipe right.

It wouldn't be that weird, knowing my sister, if they maybe have an open relationship (wasnt in his bio though, his bio was really nice and normal). She is also very depressed right now and has told me that she has told him; if he has needs that she can't deal with right now, she is okay with him finding it somewhere else

Should i tell her this or not?

They also just moved in together and have been dating for over a year.
Updates
+1 y
I told my sister about it, in a very serious tone. She had to laugh, she knows her boyfriend had a tinder account but she also knows he deleted the app when they stared dating so the account is still active but he isn't on it anymore
I found my sister's boyfriend on tinder. Should I tell her?
35 Opinion