Cousins deliberating on the same date

My cousin and I got engaged two weeks apart (pretty much the same time because my fiancé and I picked our date before he actually proposed (grey areas)).


Her and I were congratulating each other, casually chatting, and it was revealed that we wanted to get married on the same date, Memorial Day weekend. We have talked and decided that we would try to decide together who has the most valid reasons for having that date and the other couple would get married in July, as to spread the dates out as far as possible for our mutual family.
Her considerations: she’s getting married in Portugal, which is extremely hot later in the summer (heat stroke hot) and $5000 more expensive for her compared to May (off season and a holiday weekend which gives people more time for overseas traveling).
My considerations: we are getting married at our house, which we have already landscaped to be in full bloom at the end of May. Our house also does not have A/C and July is the hot, rainy season where we live.
My fiancé as be generous in his patience and flexibility, but vendors are starting to get booked so we need to set a date. We have a call planned to go over all the considerations and make a decision on who gets the date.

We have fully planned around Memorial Day and my fiancé is being very direct in wanting that date. I care about all my relationships, but I don’t know what to do?
What should we include in our considerations????