<human>: So I've been dating this lovely guy who has an identical twin, and when we first met the twin was super friendly - flirty, even - and everyone got along fine.

Now that the relationship is getting more serious, my SO's twin is ignoring him, won't really talk to me unless I make the effort first, seems generally uncomfortable - he'll leave the room if I enter, subtly, but still definitely won't hang out where I am. If we're out drinking, he's having dance offs with me and being great, but when it's sober time - pretty much just avoids me.
I know they had plans to buy a bachelor pad together, travel and meet hot chicks together, stay single and enjoy this awesome playboy lifestyle, but this is now being threatened by the fact one twin is in a relationship and happy, while the other isn't.

How can I make his twin more comfortable with our relationship? I've tried to suggest things we can do in a group, (not just the three of us as that's a little strange this early on!) but I'm also quick to get annoyed at how the 'single' twin is actually being pretty rude and dismissive of my SO whenever he's spending time with me or says no to plans because we've planned something. I know I've sort of 'stolen' his twin and I get that it must be hard for him to not have as much time with his best friend who is now all loved up, but is there anything anyone can suggest that I can do to reduce the tension in the situation?

SO suggested cloning myself so we can both be paired off and go on creepy double dates but I haven't got the resources to make this happen. As awesome as it would be!

Thanking you!

Give me the gist of the text in a nutshell
<bot>: My boyfriend's twin doesn't seem to like him being in a relationship and I want to know what might help / identify what issues he may have