I am writing a romance book. As this is my first novel, I don't know how long to make chapters or how many words I should aim for in total. How many should I go for?

For romance, aim for 60–80 thousand words. You can go longer if you want to, but that's about what most published romances come in at.

As for chapters, don't worry about how many. If you're using more than one POV, start a new chapter when your POV changes. If not, start a new chapter when there's a break in the events, or after each major beat. (If you feel like you need to breathe, the reader probably does, too.)