I [M25] was watching a movie with my friend. After the movie i saw that my sister [F21] had texted me. Apparently my mom's [F56] boyfriend [M60] had texted my sister in a weird way. It started 2 weeks earlier. The boyfriend simply texted my sister "hey, how are you". My sister already felt uncomfortable with it and didn't reply because she didn't feel like having a conversation with him. (He and my mom have been dating for around 6 months and me and my siblings have barely ever spoken to him.)

On the day my sister texted me, 2 weeks after the first text from the boyfriend, he sent her a "?". Seemingly he really wanted her to reply. My sister answered "Oh sorry i missed your text, yeah i'm good and you?". The boyfriend replied "i'm good too" and my sister said "good, glad to hear that". And then the very first text he sent after that is "Are you not yet ready for a relationship?". My sister answered "Haha no not really feeling like it, i'm still very busy with studying and work." After that he straight up said "Shall we meet up some time?". And then he sent a 🥰 emoji.

My sister sent me the conversation in screenshots and when i saw it i was probably the angriest i've ever been in my life. I just felt like beating the shit out of him. But my friend helped me to stay calm and not make any stupid choices. My sister had also sent the same screenshots to my brother [M27]. He said that the boyfriend probably doesn't mean it like that and just wanted to get to know her better because she's his girlfriend's daughter.

It just doesn't make any sense to me. If he wanted to create a bond then why does he only want it with my sister? Why does he want to meet up with her 1 on 1? Why doesn't he tell my mom about his intention to meet up with her daughter. And especially why does he do it like this over text, instead of just talking to her at our house? I feel like it's so weird if you barely know eachother to ask about how she feels about a relationship and then wanting to meet up.

My sister felt really weird and uncomfortable about the whole thing. I told her that she has to tell mom about it because this is too weird to ignore. She must have noticed i was angry and told me to not say anything and that she would say it herself. A day later i asked her if she had told our mom yet. She told her but our mom said the same thing as my brother that the boyfriend probably didn't mean it like that. I was so surprised to hear it, how can you be so naïve?

I knew i had to say something to my mom about it because it was bothering me a lot. So the day after my mom was told about it i asked her what she thaught. She again said that he didn't mean it like that and that he could've done that a bit better. I told her i'm not sure that i believed it and told her about the weird aspects of it. I told her how it's weird that he only wanted a bond with my sister and not with me or my brother. I told her that it's weird that the boyfriend texts my sister behind my mother's back. She replied "yeah it's a bit odd, but he didn't have any bad intentions". I then told her that i still feel really weird about it and it just doesn't make much sense. She replied "well then that's your problem"

I'm so confused, i feel like i'm the only one in my family with eyes and they're all blind. How can they be so naïve or am i just overthinking this? All my friends i have told this to agree that this is extremely strange. I barely ever talked with the boyfriend at all and now i prefer not to have any contact with him at all. I haven't seen him in person since this happened. In about a month i'll move to my own place and hopefully never see him again.