Why does he pull the carpet from under me?

I can’t work out what is going on … I have been with my boyfriend for 9 months.. everything is great however he gets really excited about doing things and taking me to places then changes his mind when I mention actually doing it. The latest is his sons communion in April which he has been talking about for months and it’s on my birthday weekend and I planned to drive down with my son and stay the weekend and he was very excited and put it in the calendar ( makes me plan things in the calendar for the next year so he can give to his ex) then tonight said he thinks now it might not be a good idea for me to go and I can’t go on the church and he will be clearing up all weekend.. and his ex wife’s boyfriend might go if I go but son doesn’t like him etc and I feel like things get planned but then changes with the wind …

Why does he pull the carpet from under me?
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