If I was to list my biggest dislike it'd be that it's so easy to come across as cheesy or trope-y with romances. they're written so often that it feels like everything has already been done, and coming up with an idea or a twist that hasn't been used 10k times is borderline impossible. Of course this just means that the rest of the story has to be...well a story, that's unique, so the story doesn't rest wholly on the romance as a it's plot.
It's also just really easy for me to get awkward writing romance, and figure out what's a good balance of what I should tell and what I shouldn't, how much detail I should give and when I should refrain. Both for my own comfort and other people's. I don't want to live with the regret and embarrassment of letting people read scene that got too romantic, or honestly, even if no one reads it but me, realizing with delayed-onset regret that I wrote something like that.
Favorite part would have to be the dynamic between every couple. Be it sweet, playful, spicy, or anything else, just like I love writing the dynamics of friend groups, every couple has it's own dynamics. I like writing the different ways different lovers speak to their sweethearts, react to them looking particularly pretty (or hot) at any given time, comfort them when they're upset etc.
I also like designing the reasons WHY they like each other, what started their relationships, how they lead up to confessions, the things that keep them hesitant, or if they aren't hesitant at all, what challenges those couples face, how they work through their issues together.
basically all of it, I love writing romance, and even if the story isn't a romance strictly, the dynamics of different couples. I love love, so virtually every story I write includes close friendships, siblings, and couples. Might be cheesy, but it's how I view the world, and another way my writing reflects my ideals, that love is the most important thing in the world and both conquers, (and heals) all.