My female best friend is distancing herself from me because of her boyfriend?

Anonymous
So I see this girl at my new job and my original interest in her was because she was attractive to me and she seemed cool enough from a distance.No one at my job knew each other so everyone was pretty open to make new friendships.I started talking to her and we clicked in just a few short days,i found out she had a boyfriend from another co worker which I didn't really care about because I was just focused on being friends with her.To make a long story short I've known this girl for a little over half a year now and weve been so ridiculously close since the 2nd week of me knowing her.From talking on the phone for 4 and 5 hours every single night,to going out t all different times of day and night.We usually go with a group of close friends and go out every now and then as just us.Everyone at our job would always ask us what's going on and wed both have to say she has a boyfriend.Now the thing with her boyfriend is she's been with him for years now,they live in the same city yet they have like a long distance relationship.Now I've never had thoughts of going along with cheating if she wanted too,and neither has she.I respect her relationship with her boyfriend and I whole heartedly wish her the best in it.I do like her which is I think normal for any friendship between male and female,but the thing is I'm perfectly fine with us just being good friends.If anything did develop wonderful!,but if nothing did I could really care less as long as were friends.Until about 3 weeks ago we went from texting and talking all the time to her just cutting that out and talking to me maybe 3 or 4 times a day with couple word texts.I asked her what was wrong and she told me she's been feeling bad because she feels guilty that she's such good friends with me and her boyfriend practically knows nothing.I tried to talk to her to figure things out,but she says she doesn't even wanna talk/or think about ti because it makes her feel so bad.Now another detail is her boyfriend thinks hanging out with members of the opposite sex isn't innocent and just overall makes her a bad person.Platonic relationships are not fathomable with his girlfriend.So she needs space and I give it to her but she gets more and more distant by the day.I'm scared shell stop talking to me its a notion that I actually get sick of thinking about.I have talked and hung out with other girls during my time knowing her,im not obsessed with her nor insanely in love with her.Its just this person who became my best friend whos been there through everything with me,changed me as a person,introduced me to all these new experiences.Just pretty much where all her positives out weigh the negatives in every way possible is just getting further and further away.I want to give her as much space as I possibly can but I seriously don't know what I should do.Any help would be greatly appreciated.

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Anyone have any ideas?
My female best friend is distancing herself from me because of her boyfriend?
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