My girlfriend rarely flirts. Why?

temporary long distance. I always do flirty (both sexually and romantically) comments. 3 years relationship.
we see once in two months.

but other than that she only flirts when we sext or have video sex rarely.. like once in 2-3 months.

She not only never flirt, but also just ignore my attempts with smileys.
Ever had such relationships? Isn't it boring

My girlfriend rarely flirts. Why?
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