My ex-boyfriend sent me an $1,800 invoice when we broke up

• In the early stages of a new relationship it is imperative to discuss your financial expectations.
• If you fail to communicate with your partner about money, it is likely to cause resentment in the relationship.
• Establish a financial compromise that works for both of you, and be clear about your long-term financial goals.

After a breakup, some people get a mushy "I miss you" email from their ex ... but I got an invoice. For $1,800. Actually, it was $1,797.65 and included everything from "your half of the New York hotel room"— for a wedding he invited me to — to a $5 pack of cough drops.

Shocked, I reread the bill several times. Then I realized I shouldn't have been too surprised. After all, my ex (let's call him Kevin) and I had never been on the same page, financially speaking, in the two-plus years we dated.

I thought back to the beginning of our relationship. Had I missed the signs of our financial incompatibility? In a word: Yes.

The red flags

When Kevin and I first started going on dates, he'd choose some really nice places and insisted on paying. A few dates in, he invited me to dinner and asked me to split the bill.

I told him splitting the check was too business-like and said I'd prefer if the invitee pays — a principle my grandmother instilled in me early on. I also told him I preferred handling money in a way where the person who makes more pays a higher percentage of joint costs. Since Kevin earned more than I did, we decided he'd pay for dinners and I'd pay for less expensive meals out, like lunches. (That is, of course, unless I did the inviting, in which case I'd happily pick up the tab.) Kevin agreed to go along with this, but not without resentment, I'd later learn.

This continued on and off throughout our relationship.

For instance, we once went grocery shopping for his friend's barbecue, and I tossed a pack of gum onto the conveyor belt at the checkout. Kevin not-so-subtly put the plastic grocery divider between the barbecue items and the gum. Another time, we were invited to his friend's birthday dinner at a trendy L.A. restaurant and everyone paid for their significant other, but Kevin wanted me to pay for myself. When these types of occasions were reversed and we'd go to my friends' events, I would just pay for the both of us since he was my guest.

So when, after more than two years of dating, he invited me as a plus-one to his friend's wedding across the country, I asked who'd be paying. He said we'd pay 50/50 ("like my parents do," he reasoned). But I wasn't into it. I told Kevin I couldn't afford to go (which was true), I didn't have paid vacation days and, based on principle alone, no thanks.

"What if I buy your plane ticket," he proposed, "and we can stay with my parents to avoid the cost of lodging?" I eventually caved, and we didn't discuss the wedding budget any further. This turned out to be a critical mistake.

While at the wedding, more and more unexpected expenses came up, from the hotel we spontaneously booked the night of the wedding to a fancy brunch the next morning. Yes, both of those items ended up on the invoice — well, my half of them, at least.

Looking back, I can't help but wonder what Kevin and I could have done differently to avoid the wedding catastrophe — and money tension in our relationship overall. I turned to two experts for their tips:

Start the discussion early."It's never too early to begin to ask questions about finances," says clinical psychologist Dr. Suzana Flores. Yes, this goes for the small stuff, like how to split the bill on your first few dates. But even as your relationship progresses, it also means heading off potential issues each time something big happens. For example, Flores recommends couples going on their first vacation together discuss financial expectations early in the planning. (So, unlike me, before the trip.)

Work to reconcile financial differences — or know your limits if you can't. A major point of contention was that Kevin was extremely strict with his budget, whereas I tend to be more flexible. This was bad news from the start since financial incompatibility is often a deal breaker, says millennial finance expert Erin Lowry.

Be open about your money goals."One way to avoid this situation could've been to tell each other more about your individual relationships to money and discuss your individual goals and budgets," says Lowry about the wedding disaster. "Then perhaps you could've set a financial goal together — like saving up for a trip."

Where I landed with that whole invoice thing

I didn't pay it, but it did teach me a lot about how to approach money in my future romantic relationships. It's not like I'll kiss a boyfriend goodnight and then say, "Hey, how are your spending habits?" But I will pay attention to money cues and not avoid the topic, no matter how awkward it may be.