is it an issue ?

so my boyfriend has a 7 yr old from a previous relationship and then its me we been together for 6 years with two kids.. yesterday i found out he sent her flowers and we had an argument he said “ well she has my son and i want him to see that hes 7” .. am I wrong but i thought that was for mothers day idk if i should let it go or break it off because I personally feel valentine day is for couples but i can be wrong.. he always spend the entire day with me so i know he didnt see her