I've been good friends with Lindsay, a coworker of mine, for about a year now. We work together on some projects, eat lunch together often, and usually take coffee breaks together. We spend time with each other outside of work (in a group setting) once or twice a month. We frequently ask and give each other advice about whatever is going on our lives. What I'm basically saying is that we have both a great work and personal relationship.

She has a boyfriend who I am also friends with. In fact I urged her to give him a chance when he was pursuing her. She finally did and they have been happily together for six months. I have no romantic interest in her and she doesn't have any in me.

Anyway, it was my birthday recently and she hosted a small get-together at her place. It was fun and I am extremely appreciative of all she did for me. At the party, I met her roommate and best friend (also 25F) and took a liking to her. I didn't hit on her or act inappropriately towards her, afaik. On Monday at work I asked Lindsay about her roommate and how she would feel if I asked her out, especially since there's a large age gap. I asked Lindsay if she thought it was a good idea or if I should let it go. I said to think about it and let me know because I don't want to make things weird.

Well, ever since that conversation, things have been weird. She's been very chilly to me. She's avoided getting lunch with me, kept our conversations to the bare minimum needed for work, and has had a clear change in her demeanor towards me. She was tentatively planning another party this weekend, but I haven't heard anything about it since our talk.

What did I do wrong? Do I ask her about it next week? How do I return things back to the way they were? Or is everything just in my head? I'm so confused.