Why do my friends hang out without me?

so i’ve been in this friend group for years and lately i’ve been getting this feeling that they don’t want to be my friends. we have different interests which is fine i share that with a lot of my really close friend and it’s never been an issue. the thing that really set me off. they made plans with me in a couple of days but i’m going away on a trip and asked if we could move it to a different day since they do that for everyone else. it started ok and they started changing the plans before they complained that they couldn’t go bowling. I don't know why they couldn’t maybe it was booked but either way i thought they’d rather hang out with me since i haven’t seen them in months. (due to covid i wasn’t seeing them till we got vaccinated to be safe since my circle is large) nope because they couldn’t go bowling when i got back they moved it back to the day i leave. i told them that i couldn’t cancel my trip and they acted all sad and stuff but i’m getting this feeling that they could care less. how should i approach them?
Why do my friends hang out without me?
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