(First of all, I'm not English speaker, so please, forgive my mistakes)
Yes, I totally agree! Me and my friends form Polish Forum dreaming about Love Pack! And I think, that Simmers from other countries will agree with me. We need more love!
And not only because romantic interactions are very poor... Did you see "kiss" on the couch? It's just like your mommy kissing you goodbye. On the other hand we have very nice animation before woo-hoo in the closet!
Many people complain, that their pair of lovers do not interacting like lovers do. But when the neighbor shows yourself in the area, one of our "love birds" wants to flirt with him. Why? i like romances with complications (Pride and prejudice is one of my beloved books) but at the end I want to have loving marriage. I loved when in The Sims 2 I could make a couple, who started romance without my help.
In The Sims 4 I think, that we have hidden attraction system! Some of our Sims started romance faster, some slower, and some rejecting all romance interactions and need flirty moodlet to full the pink romance bar... why?
I'm 90% sure, that there is a system and the producers hide it! You can check it with "ask risqué question". The question works like "do you like what you see?" In The Sims 2 (99% sure!). The Sims reacted in different ways - from anger to acceptation and blow kiss. I think, that depends on attraction level. Now I have a couple, who almost always answers positive (only exception, when they are in very bad mood or after they broke up). And I just said, that they acting like "three bolt" couple from The Sims 2... When they are free (not sleeping, using toilets...), one of them always starting friendly or romantic interaction... they woohooing 3, 4 times per day! (My God!). :)
I've made a little investigation. My two roomies used (on the beginning) RQ and when it was negative, I reset the game and changed them in CAS. I discovered, that after I changed my female Sim hair (from red to black), the guy immediately started to dream about her and accepted RQ with blow kiss animation! And then he, autonomously, flirted and confessed his feelings! Wow!
In different game RQ were accepted, when I changed my female Sim body type!
Next - I think, that the "attractiveness level" getting lower, when they are in bad mood. When they split, they get something like "fury" in Part 2 (temporary attraction were erased).
The main problem is, that I don't have any idea how does it works! Maybe it was a coincidence? (I started new game for many times and at the end I got what I want - they started to "like each other" very much... Sometimes after many, many resets and visits in CAS...). Maybe it's based on the looks? Main aspirations? Skills? Traits? I don't know!
That's why I dream about new pack! I must know why my male Sim prefers strange girl from discotheque over his own wife! The Sims 4 for now is a game for single Sims, who like to dating with many others... At least you do not feel sad and angry, when your dream couple not match very well...
Best regards!