I disagree. I agree with the basic premise that basic human behavior / urges in terms of seeking relationships, sex etc ultimately boils down to the instinctive urge to spread ones genes. Nevertheless, I don't feel at all that that underlying explanation makes any relationship I have any less meaningful on a spiritual and / or romantic level.
Reality is still the same. My bond with my wife is still the same. Our attachment is still the same. The fuzzy feelings we get when we share a candle light dinner remains the same. Regardless if, at bottom, we can explain our "need" for such relationships with instinctive biological urges or not.
This is an assumption.
I assure you they would still experience love like any other human.
Emotions are very real, regardless of the "mechanistic" biological explanation.
But it is............
Why would you be angry about that?
We are social creatures. We thrive in groups, we seek out companionship, we have psychological urge for "belonging" etc.
I don't see how this makes any of those things less meaningful.