My brother graduated from college, that my dad paid for, and moved back home, rent free. My dad let my brother use his credit card to take friends & a friend's family out for meals, paid for everything and even put money towards my brother's annual taxes and his retirement account. My dad had a credit card that earned cash back and even went so far as to put the cash back into my brother's account!! So my brother 'earned' money in his account by spending my dad's money !! My brother had never even paid for his own gas for his car until he was 50 years old. My brother only started paying his own bills because my dad got seriously ill and admitted into the hospital and I told my brother to stop using the credit card until my dad was 'with it' enough again to authorize it. Well, my dad was ill enough that he was in and out of the hospital and rehab for 3 months and then moved into my home and could only read at a 3rd grade level for a man that had two Master's degrees. That was over 6 years ago and my dad's delirium has resolved and he is actually healthier than before in many ways. Of note, when I went to pay my dad's real estate taxes while he was in the hospital, the money in his checking account was about 1/2 - 2/3 of what the average monthly credit card bill had been. Apparently my dad would just take extra money out of his retirement account to cover any shortages. My brother treated his friend & her family to restaurant meals at least weekly for like 25 years. Basically, my dad went through a huge chunk of his retirement monies supporting my brother's friend's family including purchases of dog food at the pet store for their dog !
My brother was in for a rude awakening when he was cut off. He still lived in the house rent free for about 7 months ( including cable, heat, etc), but he was suddenly responsible for paying for his own car insurance, own food, having to find an accountant, etc. He moved out of the house when we went to sell it and at least monthly for the past 6 years he talks to my dad about how he has to budget things and worries about his rent being raised.
My dad did my brother NO favors and neither one of them listened to me when I spoke up about it years and years ago. Now, both my brother and my father realize it was a mistake and that they fell into a habit over time. My brother had a job all that time and could have at least paid for his own clothes, gas, taxes, etc. No, my brother didn't do anything to help / be of assistance to our father that would have made it more reasonable to garner at least some of the financial handouts. He didn't even keep him company really, as he worked overnight shift, so saw my dad when he got up for dinner that my dad cooked. My brother spent most of his time off with his friends, including trips to Disney.
Break the cycle now, while your daughter is still on the young side. If you feel badly about it at all, you can put some of the funds away for her and give it to her a few years down the line if she gets into a bind or needs help with a down payment on a house or car. Or you explain you would like her to pay rent, but some of the rent will go straight into her ROTH or IRA and the rest will go to you & your husband.
If you have concerns about the boyfriend, I would open separate banking accounts that he would not inadvertently be able to access. It is kinda nice to be able to see what your daughter's accounts show and would be interesting to see if / how her spending habits change if she has to pay rent. Your daughter, if she is supporting her boyfriend or friends at all, my look at things differently once her budget is tighter.
My post was longer than it should have been, but it feels good to vent a little and will hopefully be helpful for you. Decades of trying to get my dad to open his eyes and and see he was hurting both his own financial security and my brother's ability to learn to fend for himself, drove me crazy. My dad just thought he was being nice.