small group rather than big group

It’s always more comfortable to go out in a small group rather than a big group of them. Four people and above is considered as a big group for me already. I can be talking a lot when going out with a big group of friends but it just won’t make me feel as comfortable as talking and walking with just one or two friends. I just don’t like being too focusing on talking to one of the friends among the group as it causes me to have to sort of ‘ignore’ the presence of others which I am afraid will lead to someone feeling being left out. I don’t really like being unaware of the presence of the left-outers. I don’t know why there will always be a strong sense of obligation in me in making sure of no one will feel left-out when we are out in a group. I will fail to do if I’m too engaged in talking. As the obligation of ensuring everyone is enjoying the big outing is pushing me so hard, often, I can only put 50% of my attention when involve in a conversation which will make me feel guilty again. Probably this is very weird for you but that’s just how I feel. I feel being insincere if I don’t pay full attention to what others are saying. Sometimes, it’s tiring to have to be kept pressing by the obligation but I just can’t stop myself from doing that. To avoid the ‘obligation’ and therefore the ‘ tiredness’ and ‘guilty’, I would just prefer going out with one or two friends rather than a big group of friends. It’s quite common to have silent moment when there are less people going out together but that’s still fine for me. I don’t need them to talk a lot or trying very hard to make conversation. I just need them to be themselves when they are with me.