Being gentle... your first six paragraphs are what we lovingly call "info dumps" - background stuff that in this case went on. And on. And on. Too much! If it's necessary (not much of it was) weave it in later, bit by bit. Once you got upstairs to the office the story began proper. OK, the earth didn't move for me, but Jon and Deborah were portrayed well, I got a sense of her confidence and earthiness, his lust.
But then... with all the mention of ages (Deborah is in her "mid to late twenties", the son is "six years younger") I start doing the maths - so she's 27 or 28, OK, he's 21 - 22. Wait, then he's a teenager (Lit rules, he's 18), but he's then stated as 19, and then just before his twentieth birthday. And now I'm confused....
That's the problem with info dumps - readers start using the information. But I shouldn't be doing maths in my head when there is a long legged woman to see - my point here is the unnecessary information gets in the way of the story, big time. Then you give us her bra size and there are numbers everywhere and I conclude the kid's an accountant and the story is dead in the water for me.
Which is a bit of a shame, because you've left little snippets of goodness.... Your writing is constructed well, dialogue OK, good grammar and spelling. You can write.
Ponder how your story might work if it started with Philip climbing the stairs to his dad's office....
Welcome to Lit writer's world, good luck, develop a thick skin, and keep writing. Make the earth move!