Why would a friend say she can’t imagine me in a relationship?

We were talking about dating and she revealed to me that she couldn’t imagine me being in a relationship. It took me aback because I’m wondering what she couldn’t imagine possibly mean by that?

There have been other people that have been surprised at the fact that I had a boyfriend (during the times that I was in a relationship).
Why would a friend say she can’t imagine me in a relationship?
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