My girlfriend expects me to pay for her daughters' school and food. I'm not ready to be a stepdad yet — how do I set boundaries?

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• For Love & Money is a column from Business Insider answering your relationship and money questions.
• This week, a reader worries that his girlfriend expects him to be a stepdad figure to her daughters.
• Our columnist suggests he reflect on whether he's willing to make compromises, given their different life stages.
• Have a question for our columnist? Write to For Love & Money using this Google form.

Dear For Love & Money,

I recently moved in with my girlfriend of three years. I am 29 and she is 35. She had a previous marriage and has two daughters; this is my first long-term relationship. Before we moved in together, she was careful to limit my relationship with her daughters. I understood she was trying to protect them from getting too attached, but now that we've moved in together, I guess she trusts my commitment more, and it seems like she expects me to go from a fun guy she brought around once in a while to their stepdad, including financially supporting them.

We agreed to a financial arrangement that worked for both of us before we moved in. We split the rent, utility bills, streaming services, and other expenses evenly. We should have discussed groceries, but didn't. I planned to help out now and then, but mostly only pay for my own. She wants me to split the food costs, even though there are three of them and only one of me. She's also put me in a position to pay school fees, take her daughters out, and cover other things that leave me paying for them. Her ex also pays child support.

I really like this woman and want this to work out, but I have goals, and I'm not yet financially or mentally ready to be a stepdad. Is it too late to set those boundaries?

Sincerely,

Too Fast

Dear Too Fast,

It's clear that you and your girlfriend are at very different places in your lives; this is your first serious relationship, while she has already lived through a marriage and divorce. While this gap isn't insurmountable, closing it will inevitably entail a great deal of compromise. And as your girlfriend's life is shaped by the responsibilities that come with being a parent in her mid-thirties, that compromise will mostly have to come from you.

Whether or not you feel ready to be a stepdad, any time you pursue a serious relationship with someone who has children, it's a package deal. Kids are powerless in their parents' love lives but unavoidably impacted by them. This becomes even more true when you decide to join households and move in together. As an adult who has committed to a relationship with a woman with two daughters, you have a responsibility to make sure that impact is, at the very least, minimally harmful. This means figuring out how sure you feel about your partner — and the two children who come along with her — as soon as possible.

It's fair that you feel thrown off-balance by all of this. Going from your girlfriend's daughters being minimally present in your life due to her protective instincts to suddenly being expected to treat them like your own children is quite an abrupt adjustment that most of us would struggle to navigate. However, it's also understandable that, now that you've decided to join domestic lives, your girlfriend doesn't feel it's possible or desirable to coexist separately anymore.

So, to answer your question, "Is it too late to set boundaries?" I have to be honest: In this situation, setting strict boundaries isn't really the answer. I can see what you may be imagining — grocery shopping for yourself, quietly stepping aside while your girlfriend pays for her daughters' ice cream, and not being bothered with the tedium of her children's administrative needs, let alone their school fees.

The problem, though, is that your girlfriend is a mother, and her girls are a significant part of her life and her identity. Erecting boundaries that separate your relationship from those other parts of her would effectively communicate that you'd prefer to avoid half of who she is and how she lives her life.

None of this is to say you must either completely finance her and her children's lives or end your relationship. Talk to your girlfriend honestly about what you need and what you're willing to give. Share your own financial goals with her, as well as your concerns. Perhaps there are some shared bills you're willing to split without getting into nickels and dimes, but others, like their school fees, that you'd prefer not to be responsible for.

However, also be prepared for her potentially having different expectations. With open communication and a mutual commitment to supporting one another's dreams, conversations about how much you want and can afford to spend will help you both get more clarity on whether you can make this work.

However, this issue goes beyond just spending money; as you said, you don't feel mentally ready to be a stepdad. That may be the case, but you must recognize that your girlfriend's life is a one-way train that has already left the station, and her daughters are her priority. You'll either need to hop on board or find a different route to your destination.

In other words, you can't just be the shadowy boyfriend figure hiding in the back bedroom until the girls are with their dad for the weekend. Joining lives with your girlfriend requires you to participate in the household as another adult, even if not necessarily as a full stepfather figure. Sometimes this will mean grocery shopping for the whole family, giving the girls a little spending money because you're the only one with cash on hand, or simply joining in on family game night.

If anything about that description made you wince because it sounds boring, expensive, or annoying, examine that reaction with nonjudgmental curiosity. Maybe you aren't ready to sacrifice your young adult years for someone else's family. If so, not only is that understandable, it's perfectly OK. Sometimes what people need from each other just isn't compatible, and it's no one's fault. But if you look into your girlfriend's eyes and realize being with her (and her daughters) is what you want, it's important that you talk to her and figure out how you can make that work together.

No matter what you choose, you may always wonder about the road not taken — what if you leave and she was the one, and you could have settled into a cozy family life with the woman of your dreams? Or if you stay, what job opportunities might you have chased if you'd left? Who else might you have met? What family could you have built from scratch?

The key is deciding which "what if" you can live with, and which you have to experience for yourself.

Rooting for you,

For Love & Money

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