Some people just have difficulties with emotions, especially if their childhoods had any emotional irregularities.
The best way for you to get some time focused on you is to get some time when you're the only one physically present, with other forms of communication turned off. If she likes him, it will be unreasonable to expect her not to give him dove eyes. If you're there also, then you're going to see it. It's not inconceivable that she won't even realize she's doing it, such is love. So when you're all together, you'll just have to learn to cope with it. If that doesn't work, you can also stop being all together.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker