I think this affix-riddle uses three homophones rather than relying on the exact spelling of the affixes, and the answer could well be:
My prefix is what you might do with your date.
You and your date might go out for a romantic meal and DINE in a restaurant.
You and your date may use my infix as a pronoun to refer to the two of you.
Together, the two of you would describe yourselves as US.
You would be happy if your relationship between the two of you does my suffix.
You have high hopes that your love might metaphorically SOAR, making you both feel like you're 'flying high'...
All together, I am the last thing you would want to date.
Put it all together - DINE-US-SOAR - and you wouldn't want to date a DINOSAUR! (Old and set in their ways, or fierce and inclined to eat you...)
Unless, of course, you're a palaeontologist - then you might well like to carbon-date one!