Me and my bf started making money online. We made 710.10 this year. Since we are both on the count but not married do we just split the 1099nec. It’s small $ if we split.

ask whoever told you that you don't have to claim if they will pay your taxes, interest and penalties if caught. All income must be reported. The IRS might even catch this since the one whose SSN is first on the account might get a 1099-NEC or MISC for the full amount. 

I leave open the question of whether this is a partnership that needs to file a partnership return to properly split the income and expenses. 

All amounts, no matter how little are reportable income. 

" I’ve been told if we split it we don’t have to claim it because it’s so small" only means that the people who paid you don't have to issue a 1099-NEC, if it's under a certain amount (usually $6000.  But, you still have to report the income, no matter how little.

The one who got the 1099-NEC reports the whole $710, then claims a deduction for the half the other person got. Then the other person' reports his half.  For simplicity, you may want to not take the deduction, so the other person doesn't have to report it. 

Technically this should be filed as self employment income, meaning you have to pay social security and Medicare tax, in addition to income tax.  But, if this was a one time gig, you can report it as "other income" (it's harder to take deductions for other income).  At least one of you needs to file an amended return, to report the income.  Wait until your first return is fully processed.