^He has a point TS. Though wa ko kaexperience ani myself, but naa koy mga close friends nga girls nga mag-ingunana pd. pero di nako kaila ang guy, so sa girl ra ko taman makaadvise.
there is also a concept of the "trophy wife." harsh, but it's a fact that some people choose a partner to be praised that he/she got a "keeper" of a catch. that doesn't mean he/she will be loyal to that particular partner. (S.C.) in short.
to your #1 Q: in filipino culture, *** is somewhat of a taboo topic, rarely is it discussed in depth in most relationships. the couple must have the courage to talk about how to compromise in pleasuring each other. there are lots of reading materials on this, look it up.
#2 not entirely true, some men even prefer older single women to younger ones. as the genetics, yes, people choose their most compatible partners based on traits if they can produce a healthy combination (this is usually unconscious) it might be what you call, "chemistry." (but in your stated case it's lacking timing) LOVE = Chemistry + Timing. (sadly i lack the latter most of the time)
#3 plausible, humans are insatiable, it's a fact. though a number of couples retain that spark in "literally" until death do they part.
it takes 2 to tango, both should make that effort in maintaining that intimacy, find something that strengthens that bond. before you know it, looking for someone else wouldn't be in your dictionary.