You and I decided — in the end — to get married (3)
I believe the answer is:
wed
'get married' is the definition.
(synonyms)
'you and i decided in the end' is the wordplay.
'you and i' becomes 'we' (we means you and I).
'in the end' says to take the final letters.
The last letter of 'decided' is 'd'.
'we'+'d'='WED'
'to' acts as a link.
(Other definitions for wed that I've seen before include "Took in marriage" , "Marry" , "Joined in the dew" , "Married" , "Join" .)