Hi,

When lovebirds are ready old enough they will mate. You need to put in a nest-box with some wood-chips.

Are your sure that the second bird is a female? Two males will behave like a true pair and even mate! gay-birds!

If it is a female, then she may be still too young. I suspect that your second bird is only 6-8 months old to date. At 10 months or so they will try to breed. It is better to delay breeding till she is a year over. Many young females died during their first few clutches as their bodies are not ready.

Regards