My friend told me this but I don't really think it's true?

Hi my friend told me that if me and my boyfriend still sleep together and enjoy it and kiss through it wiles he's got a girlfriend we must still like each other but we don't like each other in that way anymore and I tried to explain to her that even though ex's use to go out even anyway person can sleep with someone they don't like they don't have to have feelings am I right or is she?
My friend told me this but I don't really think it's true?
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