No, I don't believe you can "love too much".
However I do believe it's possible not to love yourself enough!
Can a parent love their child too much? No.
If a man lays down his life to protect his family from intruders does it mean he loved his family "too much"? No.
The only instance I ever hear of someone "loving too much" is when a (woman) proclaims that she loves a (man) too much.
Most likely she's not referring to being willing to die for him either!
Whenever someone states they love someone too much what they're really saying is they bend over backwards to "make the relationship work" while their mate puts in little or no effort.
One would only believe (they) love too much if they felt their love was not being reciprocated.
It's not that they love "too much" but rather they don't love themselves "enough" to choose a mate who will love them the way they want to be loved.
Anyone with a healthy self-esteem has "boundaries" and "deal breakers". They won't allow themselves to become a doormat.
There are only two ways to experience joy and peace of mind in relationships: We either get what we want or we learn to be happy with what we have. Accept them as (is) or move on.
"Never love anyone who treats you like you're ordinary."
- Oscar Wilde