Awww, hun. He does not love Daddy more!! 3 months is when they start really noticing their surroundings. He's looking at your H b/c he is there. Every time DS1 walks into the room, DS2 stops what he's doing to seek him out. Doesn't mean that DS2 loves his brother more than me!! Just means he's distracted by another person.
No one can replace mama, I promise!!
I was a SAHM mom when my first was a baby and he literally screamed if my husband came in the room. It was very hard on my husband. But like everything with kids, it was a phase, and without notice, my son's face lit up if he saw Daddy. What helped for us was to have my husband spend time with my husband without me anywhere in sight, sometimes not even in the house. The beginning was rough because my son would flip out, but since I wasn't there to distract him, he'd eventually settle down and he and my husband got their bonding time.
Kids will go back and forth with having a "favorite" parent. My older one is definitely in his "daddy" phase right now. That has its ups and downs. My husband enjoys being the "favorite," but he's also the only one my son will allow to brush his teeth, read him a bedtime story and put him to bed, so it gets tiring.
You will always be his momma and he loves you. Likewise he will always love daddy. There are no favorites; especially at 3 months.
FYI...you will be going through this off and on for several more years. My 4 yo often plays manipulator when she doesn't get her way.